The Key to Biome Farming: AFK farming every biome... simultaneously!?!

Darkstar01

Official Terrarian
This is a guide that I originally released on Steam. There have been some minor formatting alterations to accommodate this site, but it is otherwise essentially the same as the original. If you found this guide helpful, please consider visiting the original guide page and giving it a thumbs up: http://steamcommunity.com/sharedfiles/filedetails/?id=796825738




A straightforward how-to on farming biome-specific items, such as biome keys, souls, and unique weapons, from several different biomes at once. Includes pictures.





Introduction
What? The Pirate Map has a 1% drop rate? How am I supposed to get the discount card now? O Crimson Mimic, Crimson Mimic, wherefore art thou Crimson Mimic? I WANT MY UNICORN APPLE!!!

These thoughts and others like them accost the minds of many who seek biome-exclusive items. If only there were an efficient (and possibly AFK) method of farming for such things... But there isn't one.

There are several.

A few things to note going forward:
1. This guide is not exhaustive on the topic of AFK farm building. Nonetheless, while it places an emphasis on farming biome-specific drops, the farm schematics discussed here should still be suitable for general use (e.g. present farming). (For setups more advanced than are present in this guide, I recommend checking out ZeroGravitas and DicemanX's work)

2. Click on an image to enlarge. If it's still too small, right click and open it in a new tab, where you can zoom in to full size. Unless... there are browsers that don't let you do that. I mean, you should be able to, right? Note that this shouldn't actually be necessary here, because unlike on Steam, images automatically attempt to display at full size.

3. Uh... yeah, I actually only had two. Feels kind of silly making a whole list for just two items, huh? So anyway...



Loot Table
After some contemplation, I decided that this section would best serve as a preface to the building instructions, rather than the reverse. Peruse this section to find the items you want, so you can better utilize the following sections in determining where and how to construct your farm. This table only includes info for items dropped by multiple enemy types; if you're looking for a very specific item, you can check the Terraria Wiki.

Biome vs. enemy priority refers to whether the item will drop from most enemies in a biome (including non-natives), or from one or more specific enemies that spawn in that biome. The one odd case is the dungeon, in which Ectoplasm dropping is technically enemy based, since only Dungeon Spirits drop it, but is listed as biome based because the spirits themselves randomly spawn only when another dungeon enemy is killed.

It should be noted that most of these items cannot drop from statue-spawned enemies.

Entries marked with an asterik (or three) have special conditions that must be met before the item in question will drop. These are covered below.


Item Name
------Sprite--------Biome-------------Drop Priority-Drop Rate-Drop Rate (EX)
Biome Keys*
---Namesake Biome----Biome--------0.04%------0.04%
Soul of Night*
----------Underground 'Evil'------Biome--------20%----------36%
Cursed Flame*
-------------Corruption------------Enemy-100% (33% for Vile Ghoul)-Same
Rotten Chunk
-------------Corruption-----------Enemy-----------33%--------33%
Ichor*
---------------------------Crimson-------------Enemy-100% (33% for Tainted Ghoul)-Same
Vertebrae
--------------------Crimson------------Enemy-----------33%---------33%
Soul of Light*
----------Underground Hallow---Biome-----------20%---------33%
Blessed Apple*
--------------Hallow---------------Biome-----------0.5%--------0.67%
Yelets**
-----------Jungle (including Temple)-Biome------------0.5%-------0.5%
Lihzahrd Power Cell
--Lihzahrd Temple-------Enemy------------2%----------2%
Solar Tablet Fragment
--Lihzahrd Temple---Enemy-----14.29% (1-2)-14.29% (1-2)
Amarok*
-------- -----------Tundra------------------Biome---------1.25%--------1.25%
Antlon Mandible
--------------Desert----------------Enemy----------14.29% (normal) (1-2), 33.33% (charger, swarmer) (1-2)-Same
Pirate Map*
-------- ------Ocean----------------Biome---------------1%-----------1%
Cascade***
--------Underworld and bottom caverns-Biome-----0.25%----0.25%
Hel-Fire*
------Underworld and bottom caverns-Biome----------0.5%------0.5%
Living Fire Blocks*
------Underworld--------------Biome--------2% (20-50)--2% (20-50)
Bone
-------------- ------------Dungeon---------------Enemy---------98.07% (1-3)--100% (2-6)
Ectoplasm****
-------Dungeon (100+ HP foe)--Biome-------6.67% (1-2)-----6.67% (1-2)


*Hardmode only
**Hardmode only, must have defeated at least one mechanical boss
***Pre-hardmode only, must have defeated Skeletron
****Post-Plantera
(If there is a method of making an actual table in a post here, I am not aware of it.)


Farm Construction 101
Before determining all of the specifics of where to build a farm and what materials to use, it would be helpful to develop a basic understanding of what an efficient farm looks like.

First of all, you're going to want a nice, flat and open area. It doesn't strictly have to be flat, but if it isn't wide and in the open, enemy spawns will be constrained. This is a more serious issue underground, not only as a result of the naturally cramped quarters, but also due to the fact that enemies can spawn in crags and caverns beneath you. Even if you are building a farm on the surface, it would be wise to check out the area below you, and fill in any holes you find with blocks or backwalls. Player-placed backwalls will inhibit enemy spawns, but natural ones won't.

When choosing where to spawn an enemy, the game will select an empty tile that does not have player-placed backwalls on it, and spawn the enemy on the ground below that point. Enemies will spawn a minimum of 63 tiles to the left or right of you, and a maximum of 84 tiles. The chosen tile will also be between 35 and 47 tiles above or below you. With that in mind, an optimal farm should have at least 84 blocks on each side of you, and, assuming the ground below you is well insulated, have at least 47 tiles of space open above the farm. How precisely the farm is constructed will depend on whether it is intended as an active farm or an AFK (away from keyboard, i.e. automatic) farm. The area below you doesn't necessarily need to be completely insulated, as enemies will not spawn in areas that are on-screen. Thus, for a stationary AFK farm, at least, holes that are visible from your resting point won't need to be filled in.

...perhaps an illustration would be of use.

Pro-tip: You can easily measure out distances without needing to use the in-game ruler, by separating your building materials into stacks manually. If, for example, you right click to remove some conveyor belts from a stack until the original stack has 84 remaining, then you can pick up the original stack and place it all out. Once the stack runs out, you will know you have used 84 units, and hence that your conveyor belt is 84 blocks long.

Active farms generally need to be larger than the minimum specifications, as you will be moving around to fight enemies, and thus spawn surfaces will change in relation to your movement. However, the farm won't need to be on even terrain, since you'll be collecting the loot manually. Active and AFK farms have their respective strengths and weaknesses, most of which should be fairly obvious. AFK farms don't need constant input, but can't be used to efficiently farm events (e.g. pirates) unless you frequently check the game and restart the event whenever it finishes. Their construction also requires a means of automatically collecting loot, as there is a limit to the number of stray items that can exist in the world at any given time. If too many uncollected items pile up, they will start despawning to make room for newly dropped items. Bear in mind that events can be used as a conduit to farm biome-exclusive items, such as summoning the eclipse in a tundra to farm for frozen keys and Amarok. You can even use the pirate invasion to farm for Pirate Maps in the ocean...

With an active farm, you can kill the monsters with whatever you like, but an AFK farm will require traps of some sort, or decent summons. You could place dart traps facing outwards to attack monsters at range, or actuated spear traps in the air above your spawn surfaces (blocks 63-84 to each side of you).

You'll want everything you can get to speed up the killing process, so be sure to place some banners of the enemies you intend to fight, as well as a Water Candle to increase spawn rates. Remove any Peace Candles or sunflowers you have nearby, as these will decrease the spawn rate.

Pro-tip: The Eater of Worlds has 50 separate hitboxes, each of which drops loot independently of the whole unit. The Eater is capable of dropping biome-related items (other than souls), and thus can be an efficient farming target for an active farm. For example, killing the Eater in a corrupted tundra gives each of the boss's segments a separate chance to drop Amarok, a Frozen Key, or a Corruption Key.



Biome Requirements (and how to meet them)
Biome Requirements:
In order to acquire biome-specific items (such as keys), the biome in question must be active. While it isn't actually possible to farm all biomes simultaneously (due to the fact that Crimson/Corruption and Hallow counteract one another), you can farm for every key except the Hallowed one within a single setup. The requirements for activating our biomes of interest are as follows:

Corruption: A minimum of 200 Corrupted blocks ( ) Corrupt thorns also increase this count. Each Hallowed block present reduces this count by one. Each sunflower present reduces this count by 40*.

Crimson: A minimum of 200 Crimson blocks ( ) Crimson thorns also increase this count. Each Hallowed block present reduces this count by one. Each sunflower present reduces this count by 40*.

Hallow: A minimum of 100 Hallowed blocks ( ) Each Corrupted/Crimson block present reduces this count by one.

Jungle: A minimum of 80 jungle blocks ( ) Jungle vegetation also increases this count.

Lihzahrd Temple: Technically, the only requirement is that you be standing in front of naturally-generated Lihzahrd Brick Walls (). Removing natural walls or crafting them from blocks will not work. Because temple enemies will only spawn on Lihzahrd Bricks, it is de facto required that you use them as your spawning surface in order to actually get temple enemies. Because Lihzahrd Bricks wield jungle influence, most temple biomes will qualify as a jungle as well. You cannot build a temple in a new location, but you can hollow out the existing one and build your farm inside, as the temple is usually quite large, and has backwalls behind all of its blocks.

Tundra: A minimum of 300 tundra blocks ( )

Desert: A minimum of 1000 sand blocks ( ) This is highly misleading, however, as you need not actually activate the desert in order to farm its drops. For more info, see the enemy spawning requirements section.

Ocean: This biome automatically occurs near the edges of the world, on the surface. The background (and, usually, music) will change to indicate the ocean biome. Water is not required to be on-screen to qualify as an ocean biome, and Pirate Maps will drop anywhere within one.

Underworld: This biome automatically occurs once you go below a certain depth. The change will be very obvious, and the music will change.

Dungeon: Perhaps the most restricted biome of them all, you'll need at least 250 dungeon bricks
( ), and you'll need to be standing in front of naturally generated Dungeon Brick Walls ( ) below surface level. Removing Dungeon Brick Wall and placing it down somewhere else will not work, and contrary to many rumors I've heard about other natural backwalls working, my testing suggests otherwise. While most Dungeon Bricks have backwalls behind them, it may still be difficult to find a place large enough for an AFK farm in the dungeon, not to mention how deadly the post-Plantera enemies would be to an AFK player, as many of them have powerful, block-piercing attacks.

Now, you might think that you could meet the conditions for several biomes at once by just stuffing a bunch of their respective blocks in a small area... and you pretty much can. Infected ice is especially efficient as it counts for two biomes at the same time. The only conflicts of interest here are jungle and Hallow vs. Crimson/Corruption. In the case of jungle, this can be averted by using Lihzahrd Bricks, since these can't be infected, and are generally easier to compact than jungle grass. The conflict between Crimson/Corruption and Hallow cannot be resolved, however, so you must choose between Hallow and the other two (which can co-exist with one another). The first example farm above qualifies as Crimson, Corruption, Tundra, Jungle, and Ocean. Also, even if you activate an evil biome or the Hallow, souls will not drop within the dungeon on PC (though they should drop on the Xbox 360 version, and possibly other non-PC versions as of this writing). The Lihzahrd Temple, Dungeon, and Underworld are also mutually exclusive by virtue of the fact that they can't be artificially created (without a third-party world editor), and will not naturally overlap. Meteorite is also an insoluble biome, but Meteor Head farming is totally useless during hardmode, so you should just leave meteorite blocks out of your farm entirely.

* I know the wiki says five, but they must be talking about something else. Maybe they're referring to how NPCs react to Corruption/Crimson, rather than the presence of the biome itself, since NPCs can flee from the evil, even when the biome isn't actually active on-screen. I've tested this carefully, and I had to add exactly forty ebonstone blocks to re-activate the Corruption after adding one sunflower. Not that sunflowers are likely to inhabit your farm, anyway.



Enemy Spawning Requirements
Somewhat surprisingly, the types of enemies that spawn in a certain area often aren't dependent upon the biome in which they are spawning. Rather, the blocks on which they spawn are the deciding factor in determining what type of enemy will spawn. Biome-dependent items will drop in a given biome even if that biome isn't spawning its native enemies. You could, for example, place a thin layer of Crimstone as a spawn surface in a Hallowed area, and get Crimson enemies to spawn and drop Souls of Light.

Strangely, while Lihzahrd Bricks wield jungle influence, they do not necessarily spawn jungle enemies and are instead considered a neutral spawning surface. You may notice that even the natural Lihzahrd Temple spawns generic underground enemies on its surface if you aren't in front of natural Lihzarhd walls. Jungle bats and jungle slimes can spawn on neutral surfaces while a jungle is active, however, and because Lihzahrd Bricks are considered a neutral surface while outside the Lihzahrd Temple, they may give the appearance of spawning jungle enemies by virtue of this fact. Even with the temple as an active biome, non-Lihzahrds can spawn inside, such as normal underground foes spawning on top of wooden spikes.

Hallowed blocks also exhibit unexpected behavior when outside of their native biome. When the Hallow is not an active biome, hallowed blocks in the area will act primarily as a neutral spawn surface, though Enchanted Swords and Chaos Elementals will occasionally spawn.

Infection mimics are one type of enemy that spawns based on biome rather than blocks.
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Even in the Underworld with no Crimson blocks on-screen, it seems... which brings me to my next point.

The Underworld is a seemingly implacable biome, but it can actually be subverted by the infection. Of course, you'll need to import infected blocks to use as a spawning surface, but enemies of their respective type will spawn on them once you place some down. Enemies in the Underworld (even native ones) will also drop souls and other biome-specific items if the requirements for those biomes are met. For example:

Despite being located in the Underworld, this farm spawns Corruption enemies on the left, and Crimson ones on the right. Of course, collecting the souls automatically is tricky business, and the Clingers from the corruption side don't always leave their drops on the conveyor belts when killed, despite the placement of the spear traps. This is just for demonstration purposes, as you can clearly see the souls, Amarok, and Corrupted Mimic generated by the setup. I can confirm that jungle grass also spawns its native enemies when transplanted into the Underworld.

Another enemy whose spawning is based on biome rather than spawn surface is the Ice Golem. If it is raining with a sufficient number of ice blocks present, Ice Golems can spawn on neutral surfaces. Even during a pirate invasion, apparently!

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I also noticed a few Devourers and World Feeders spawn in my example setup from 101, despite no corrupted blocks being exposed and no other corruption enemies spawning.

The desert is a strange case in that the actual biome itself doesn't really do much, despite having the steep requirement of 1000 sand blocks to activate. Desert enemies will spawn on sand even outside of an official desert. Perhaps most surprising is that all hardened sand and sandstone is considered a neutral spawning surface. Even corrupted sandstone will only spawn generic slimes on the surface, despite the background and music indicating a corrupted desert biome. This leads me to my next point: the underground desert, which is composed primarily of hardened sand and sandstone spawns its respective enemies not because of the sand, but because of the natural backwalls that appear in the underground desert. Thus, in order to farm underground desert enemies, you'll need to build your farm in the original underground desert that generated with the world. Because they use a neutral spawning surface, you can safely cover the whole area in conveyor belts without impacting their spawns. Even more bizarrely, the exact type of backwall doesn't matter, either. I coaxed hallowed desert enemies to spawn by placing Pearlstone under the conveyor belts, despite the backwalls being corrupted.

Like the underground desert, spider mini-biomes are reliant entirely on their natural backwalls. Unfortunately, these backwalls don't extend far behind nearby blocks, so it will be difficult to find space for an efficient AFK farm there unless you get lucky with world-gen.

Meteor Heads ignore spawn surface completely, and appear exclusively once there are enough meteorite blocks in the vicinity. Unfortunately, they drop nothing at all in hardmode, and their slow movement makes them a fairly inefficient farming target even in pre-hardmode.

Enemies in space also ignore spawn surfaces and biome-related blocks, resulting in only Wyverns and Harpies spawning (though Wyverns won't spawn if you're standing in front of backwalls). While you can't spawn other enemies, you can still gain the other effects of biome-related blocks.

Granite and marble biomes have strange spawning rules that are difficult to pin down. Granite enemies will spawn on granite blocks in the underground (dirt) layer if there are natural backwalls present (even marble backwalls!), but don't seem to require backwalls when in the cavern layer. Of course, desert backwalls won't work, and will spawn desert foes. Marble enemies don't require backwalls either (at least not in the cavern layer), but won't necessarily spawn even with marble blocks abound. In one cavern layer test, a marble spawning surface yielded marble biome enemies, but in another, building the entire setup out of marble didn't yield any... until I noticed Hoplites spawning on non-marble surfaces. Then again, let's just say that I have reasons to believe the latter test may have been... aberrant. My testing indicates that both marble and granite enemies can spawn on neutral surfaces in the cavern layer if there are a sufficient number of marble or granite blocks present. However, building a farm in this way will result in normal underground enemies (and possibly jungle bats/slimes, if you activated the jungle) competing for spawn priority with the granite/marble enemies. I'm not certain that a 100% foolproof method for spawning only granite or marble enemies even exists. All I can say for sure is that if you're building a granite or marble farm, put it in the cavern layer for best results.
Just make a statue farm.

One last thing to note is that adding Lihzahrd Bricks to a farm is almost always beneficial, even if you aren't trying to get Yelets. When determining how quickly to spawn enemies, a hybrid biome will give priority to its constituent with the highest spawn rate. The jungle has the highest spawn rate among biomes that can be created artificially, and so adding 80+ jungle blocks to a setup will almost always increase its spawn rate, and by extension its efficiency. The spawn rate for underground jungle is slightly higher in the cavern layer and below than in the underground layer. It should be noted that the music and background do not necessarily match the biome with spawn-rate priority.

There are only two instances in which this would not apply, the first being if you are farming the Dungeon, as the Dungeon has the same spawn rate as the jungle. The other instance would be a farm used against events, as events use their own spawn rate, which is higher than that of the jungle.



Farm Construction 201
Now that we've covered the basics of constructing a farm and activating the desired biomes, let's get into some of the more advanced techniques (and I'm not just talking about spear traps!).

Self-Defense:
This one may seem a little too obvious, but if you're running an AFK farm, you don't want to die, right? If you die, your minons will despawn, though if you aren't using any, I guess you could place a bed in the center of your farm and set your spawn point there...

The most obvious way of not dying would be to simply box yourself in, as in both of my previous examples. This is all well and good if your target enemies can't pass through blocks, and don't use any attacks with splash damage, but if they do, you'll need to reinforce yourself. Note that many enemies that can pass through blocks won't spawn if you are standing in front of player-placed backwalls. If you don't need items from such enemies, placing backwalls inside your resting area can improve your odds of survival.

If you have minions that pass through blocks (e.g. Stardust Dragon), then you can rely on them to kill would-be attackers. If not, be sure to summon a minion within your box, so that it can attack anything that gets inside. Since these minions might not kill the assailant instantly, you'll want something for pure defense as well.

A campfire, heart lantern, and honey pool are the obvious ones, but recall that the stats of summoned minions do not change, allowing you to trade out damage-boosting accessories after the initial summoning for defensive ones. Of particular use are the Cross Necklace/Star Veil for essentially cutting the damage you take while AFK in half, the Shiny Stone for its massive heals while stationary, and the Frozen Turtle Shell and Worm Scarf for just being solid defensive armaments in general. A final defensive armament to consider is the Spore Sac. It wields impressive stopping power over a small area around you, and can compensate for lackluster minions. Note that spores will only spawn over blocks, and cannot spawn directly in water, though they can spawn within air bubbles below the surface.


You can also invoke teleporter spam by putting a teleporter in your resting box and wiring it to a one second timer. Make sure that the target teleporter isn't too far away, or the enemies in the farm will despawn. For best results, place the target teleporter box directly above the first one. Make sure the area above is cleared/sealed, so enemies don't start spawning up there when you make the jump. You'll probably get sick if you watch it run, but that doesn't matter if it's AFK, right?

The Arapaima Method:


That's a lot of banners! We're going to have that and more when we're done here! This is all made possible by the fact that arapaimas, otherwise unremarkable foes with no special drops of their own, spawn in pools of water within the jungle. This effect can be immediately seen by placing some Lihzahrd Bricks down on the ocean floor. By exploiting the speed with which arapaimas charge towards the player, and the jungle's naturally high spawn rate, we can easily farm biome specific items. It should be noted that I'm not the only person to have documented an arapaima farm; I honestly have no clue who first came up with the idea.

Basically, the setup for this farm just like any other biome farm... in SPACE water! Set up your biome farm as usual, but then submerge the whole thing when you're done. The Bottomless Water Bucket helps with this, but you could just carve out part of your ocean, and make the farm there. If you do that, ocean enemies will still occasionally spawn in the farm, but it shouldn't be too big of a deal. You will, of course, need the jungle biome active in order to spawn the Arapaimas, but the rest is pretty flexible. Another obvious point is that you need to not drown while farming. You could simply wear Neptune's Shell (or its upgrades), or cover your resting spot in bubble blocks, or whatever. With Neptune's Shell and strong enough minions, you can just throw down the Lihzahrd Bricks and you're good to go. Be aware that arapaimas will only attack you if you're at least partly submerged in water. This water doesn't need to be contiguous with the pool in which the arapaimas reside, so if you have a sealed box to rest in, place a little water in it to get the arapaimas to approach the box more quickly.

Here's a rather crudely constructed Pirate Map farm I threw together a long time ago. It lacks conveyor belts, so you would have to collect the loot manually. In my defense, they hadn't yet been introduced when I built this. That aside, the farm does more or less work... mostly.

I would make a joke about it being over 9000, except it isn't... and I wasn't about to kill 900 more arapaimas just for a joke literally two people would end up laughing at.
I've heard that in the original Japanese version, it was "over 8000"

Here's one with a bit more effort put into it:

If you build it, they will come.

Arapaimas will readily spawn on neutral surfaces, but other enemies will occasionally spawn there too. In this case, Stardust Dragon was used to kill them (though I de-summoned it to get the screenshot). For some reason, items kept getting stuck under the floor in the original version of this build, so I modified it by placing the central resting point a bit off the ground and sloping conveyor belts towards it (as pictured). Thus, the enemies swam a bit off the ground, and their items didn't get stuck when they died.

This last one can be built at the start of hardmode (because if every farm used Stardust Dragon, this guide wouldn't be very accessible, now would it?):
They're as silly as they are effective, which is to say, very. Immediately after spawning, the arapaimas will make like lemmings and lunge straight for your deathtrap. Because the bubble blocks aren't solid, larger enemies (such as sharks) can kill themselves on it, too. And, because the lava is only in the center, enemies will almost always die close enough that you'll automatically pick up their drops.

The sloped edges push enemies either up or down and (except for the occasional stubborn jellyfish...) into one of the two traps. The ideal place to put this is in the horizontal center of the ocean, near the surface. You can put it just below the water and have a lava trap on top (as pictured), or submerge just the bottom half. If you do that, make sure the edges above the water are constructed in such a way that enemies can't get up onto them.

What you see here is the entire setup. You don't need any fancy conveyor belts, traps, or teleporters; you don't need any wires at all! The only hardmode materials used are the bubble blocks. You can just place blocks in the air above the farm for whatever biome(s) you want to activate.

The biggest obstacle to construction may very well be simply finding something to anchor your initial block to. An Ice Rod can be used to create an artificial anchoring point, or you could put blocks from the ocean floor/shore to the place where you want the farm. Just be sure to remove the extraneous blocks when you're done, or they may impede enemy spawning/movement.

Pro-tip: Eclipse enemies won't spawn in the ocean, so you can use that event to massively increase the spawn rate if that's where you built your farm. It's crazy!



Farm Construction 301
Teleporter Farms:
Recall that most enemies can be teleported. With careful use of teleporters, you can cut out the non-spawning surfaces by bringing the enemies (and by extension, the loot) right to you immediately after it appears!

Bear in mind that teleporters are not unidirectional; activating a teleporter will swap the contents on both sides. Thus, if your kill box is inefficient, you may find half-dead enemies spamming the teleporter into and out of the box repeatedly. Then again, this may happen anyway, but in any event, the loot will still ultimately drop into the kill box for easy collection. Unless the enemies somehow clip through the wall, that is...

With heavy use of teleporters. you can strip your setup right down to its essential parts:

and with wiring


This setup has a lot of moving parts that probably require explanation, so... here we go.

In the center, we have our kill box, with a place for the player to rest just underneath. The bottom of the box has been augmented with Lihzahrd Bricks to pump up the spawn rate, but you could have any other biome related blocks added in whatever configuration you like. The Obsidian Brick could even be replaced with biome-related blocks. Because the space immediately under the box and to the sides of it aren't used, you can build anything you like there! You could even place this farm inside of a larger, pre-existing structure, so long as you got the spacing right (which is approximately the same as in the other examples).

The house above has a teleporter to get you into the bottom box, but it is also wired to a one-second timer that activates the spear and flame traps on the right half of the kill box. As for the left side, that involves some shenanigans up top. The spear trap on the left (in the house on top) fires immediately when the setup is activated, and after travelling 20 blocks (the same distance traveled by the spear traps in the kill box) hits its target, causing another spear to fire and travel another 20 blocks, activating the second one second timer precisely when the right side spears retract. This is a reliable and (relatively) straightforward method of staggering the traps' activations, as enemies can't be hit by multiple traps simultaneously, and thus DPS is wasted if the traps' firing time overlaps.

There is actually a minor error in the setup as shown: the yellow wire going to the one-second timer on the right shouldn't go through the left spear trap, the red wire should. This causes the timing loop to be reset every cycle, as the first one-second timer turns the second one on and off repeatedly. However, this has the same de facto effect as wiring it properly; the spear traps will still fire with the proper timing. The traps ran so smoothly that I never even noticed the error until I looked at the full snapshot after the fact.

The big boxes on the left and right are used for spawning, with a roof to prevent enemies from escaping, and lava on top to prevent them from spawning up there (though they shouldn't, regardless). You can switch out the Obsidian Bricks for whatever spawn surface your target enemies require, though bear in mind that the teleporters on the surface will act as a neutral spawning surface. There are a few ways around this, perhaps the simplest of which is to place the desired blocks just above the surface teleporters (while maintaining enough space for enemies to slip underneath), and fill in the area between the aerial blocks and the teleporter with backwalls. Some enemies (such as Clingers and Floaty Gross) can't be teleported, so if you need their drops, be sure to have something extra in place to deal with them.

The teleporters inside are each hooked to yellow (enemy activated) pressure plates, and are connected to teleporters in the kill box at their respective height. That is, since teleporters can transport entities a few blocks above them, they deposit said entities the same height above the destination teleporter. By burying some of the teleporters, we can thus stack the teleporters in the kill box up to three blocks deep, saving space. Those warped by teleporters on the surface jump to surface teleporters, and those buried one/two blocks down, to teleporters lower in the stack. If you don't understand, just look at how the wiring between the teleporters is done, and it should make sense.

The spawn and kill boxes have both been widened a little to reduce the probability of teleported enemies clipping through the sides of the enclosure and escaping. The Living Fire Blocks in the spawn boxes mark the boundaries of the actual spawning area. As you may have guessed, the conveyor belts in the kill box, while necessary for total drop collection, result in enemies teleporting slightly into the ground. The belts have been hammered to half-blocks to remedy this, and the spear traps have been placed in such a way that enemies very close to the ground won't get hit, preventing their drops from getting stuck between the conveyor belts and the teleporters.

The flame traps on top are basically just for Fire Imps (who also take damage while standing on top of the traps). Their usage may vary depending on what enemy types you're farming. There are also regular dart traps, one in each spawn box, which are simply used to activate dormant mimics, so that they can be teleported into the kill box and finished off. Using the weaker dart traps minimizes the risk of actually killing something outside the kill box.

Lastly, to wholesale prevent enemies from spawning below you, you could fill it in completely with blocks (or simply make sure there are player-placed background walls there), or you could hollow it out, and nullify spawns by covering the only open surface with lava. Though I could have sworn that I've seen Mimics who apparently spawned in lava...

Trap Timer Staggering:
If you read the above, then you know what I'm talking about (paragraphs three and four, below the second picture).

A very straightforward and customizable way to do this is to wire the initial activation to a dart trap firing down a one block tall tunnel with teal pressure pads (not to be confused with pressure plates) in it. Each pressure pad can be wired to a different timer, each wired to its own traps. By adjusting the spacing between the pressure pads, you can modify the timing of the traps relative to one another with great precision. Keep in mind that darts fired from the trap travel at 45 blocks per second, and travel at half speed in water, and 25% speed in honey.

Since traps generally inflict piercing damage, you'll want at least 1/6 of a second delay between overlapping traps, unless you have an extreme number of them and just want to fire them continuously. The fact that darts spawn two blocks ahead of the actual trap may or may not affect the timing; if you aren't sure, you can wire your first timer to a pressure pad exactly two blocks ahead of the dart trap.

Here's an example:

and with wiring





The Pauper's Farm
Maybe hardmode is still too much to ask. What if you're some poor pre-hardmoder who just wants a puppy for Christmas? Well, the Dog Whistle has a 0.24% drop rate, so good luck farming for that with your copper shortsword! If only there were a decent farming setup you could make without having to beat any bosses... You know where this is going, right?


It's really quite simple. To build this farm, you'll need:
1 Copper Pickaxe or better ;)
1 Wooden Hammer or better
79 Mud Blocks
1 Jungle Grass Seed
1-5 Wood Platform(s)
1 Water Candle
8-17 inert blocks
1 Lava Bucket
3 or more units of background wall (only for Corruption farms)

Ideally, such a farm should be located well within a Corruption/Crimson biome. You can be sure of this if only the biome's native enemies are spawning. Once you've found a nice spot, dig out a one block deep hole, five blocks wide, and pour one bucket of lava inside. Sloping the path leading up to it into a smooth incline will ensure that all but the most finicky flying enemies will land in your trap.

Place your wood platform(s) so your character's head is touching the bottom of the lava pool when standing on one. By standing in the center, you can collect most of the drops automatically. You shouldn't need to thin out the lava to prevent items from burning, either, since the drops will fly straight into your inventory without touching the ground.

The inside walls of the inner compartment are covered with inert blocks to prevent Corrupt/Crimson grass from growing inside and spreading their damaging thorns into the resting area. The wood backwalls are optional if farming the Crimson, but some player-placed backwalls should be used in the case of a Corruption farm, as they block the spawning of Devourers, which would otherwise burrow through the sides of the farm and attack you directly.

For the jungle blocks, dig a hole within your inner compartment, 11 blocks wide, and 9 blocks tall, and line the exterior with mud. Plant Jungle Grass Seed on it and allow it to grow. Use the remaining mud blocks to create a checkered pattern by filling in every other block on even rows, and all blocks on odd rows. Note that while this only gets us to 79 jungle blocks (80 are needed to activate the jungle), jungle plants will soon grow on the blocks, which count as jungle influence and will push you over 80.

As a final touch, place a Water Candle on a wood platform. Even if you haven't defeated Skeletron, there will usually be a Water Candle above depth zero in the Dungeon for you to take. The banners aren't actually necessary, as they don't affect lava damage.

This probably sounds a lot more complicated than it actually is. If anything seems confusing, just look at how it was done in the picture. You could even just copy the picture and skip the text instructions, if you prefer. The jungle grass and Water Candle aren't absolutely necessary, but both will improve the efficiency of the farm by raising enemy spawn rates.

It is worth noting that it can still be useful to build a Corruption/Crimson farm in a pre-hardmode world after reaching hardmode in other worlds. Because most hardmode Corruption/Crimson enemies don't drop Rotten Chunks or Vertebrae, respectively, farming for these items will be more efficient if done in a pre-hardmode world.



Final Notes
You thought I was done? So did I... I've discovered many unexpected things while doing research for this guide, and it has become much longer that I originally expected. There are just a few more things I have to say:

Eclipse Shenanigans:
I read somewhere that eclipse enemies can't spawn in the ocean, but I wasn't sure if that was actually true. As it turns out, they really are blocked by ocean spawns. By summoning the eclipse in an ocean arapaima farm, you can drastically increase the spawn rate without putting yourself in danger of eclipse enemies. Be aware that eclipse foes will still spawn on the shore; it is specifically the water in the ocean that blocks their spawns. But you already put your farm far enough out that nothing is spawning on land, right? A large pool of water elsewhere on the surface will reduce their spawns, but eclipse enemies will still sometimes appear. It seems that Reapers may still be able to spawn while you are standing in front of player-placed backwalls, so prepare for that if you aren't in the actual ocean.

Another place that won't spawn eclipse enemies is the underground desert. Now before you say "of course a surface event won't spawn enemies underground!", take note of the fact that underground desert backwalls usually extend well above depth zero. If world-gen is kind, you can fit an underground desert farm above depth zero, and use the eclipse to kick the spawn rate into overdrive. Underground desert enemies will still spawn above depth zero, so long as the backwalls are present.

Eclipse enemies also won't spawn in space, if there isn't a valid spawning surface for them. If you wish to farm Harpies or Wyverns with the eclipse in effect, make sure that your spawning surfaces are non-existent.

Invasion Shenanigans:
Speaking of space, events can spawn their respective enemies up there if there is a solid surface for them to spawn on. If you widen a sky island enough, and put an NPC in the house, invasions can spawn on it. It's actually rather amusing to watch goblin invaders slowly jump around in low gravity. They make good target practice with a sniper rifle; you should try it sometime.

Broadly put, invasion enemies will spawn above depth zero near the horizontal center of the world, and anywhere on or above the surface that is relatively close to NPC housing. If you build an NPC house in the ocean biome, you can farm pirates there. Due to the number of pirates killed vs. the drop rate of Pirate Maps, this will be essentially self-sustaining. Remember, the background change, not the presence of sand or water, marks the boundaries of the ocean. Of course, you'll need the actual water to spawn sharks and other ocean enemies, but if you don't need to, then anywhere in that region is fair game.

And... the rest:
So... I think I covered every biome in there, at least the good farming targets. I didn't talk about mushroom at all, but that quite frankly has no business being in a key farm or anything of the sort. Wall piercing enemies? Check. Wall piercing, long range, semi-homing projectiles? Check. Truffle Worms are not under the jurisdiction of this guide. As for Meteor Heads, I only mentioned them to warn you not to farm them in hardmode.

I feel like I left out something really important... OH! Yeah... You probably want to know how to run Terraria in the background, huh? Just minimize the game by clicking on the Terraria icon on the bottom. You'll know it worked if you can still hear sounds from the game. Just make sure you don't have something stupid active in your hotbar, like dynamite or the Rod of Discord, because you'll use it if you click! Once you know how to do it, you can set all sounds in Terraria to 0% in the menu, and then you can 'AFK' farm while surfing the web, or whatever.

Then there's the other elephant in the room: the Battle Potion. If you can be bothered to check your AFK farm every seven minutes, I guess it could be useful, but it would probably be more helpful in an active farm. It should be noted that there is a limit to the spawn rate outside of certain special events (e.g. Pumpkin Moon, Pirate Invasion). If you already have an eclipse in a jungle with a Water Candle, you're probably near the cap already, and the Battle Potion won't do much good. And if you're thinking "Well, I'll just use it during invasions, then!", you're still wrong because the Battle Potion (and Water Candle) doesn't affect spawn rates in those instances. Still, it might be helpful if you aren't using the eclipse or an invasion (e.g. your farm is underground).

AFK farming the Pumpkin/Frost Moon would require more advanced techniques than this, and isn't likely to be as efficient as other methods with regards to biome-specific drops.

I can neither confirm nor deny that King Slime's mini-slimes individually drop biome items. Even if they did, the fact that each summoning costs 5 gold/platinum bars (30 on console/mobile!) and a ruby makes it somewhat expensive.

As usual, if you have any questions or comments, feel free to leave them in the thread below, or the comments section of the original guide, and I'll be sure to answer your questions to the best of my ability when I see
 
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What if I set up an akf crimson farm in the dungeon? Will that work? All I see are souls of night smh
 
What if I set up an akf crimson farm in the dungeon? Will that work? All I see are souls of night smh
In my experience (on PC), Souls of Night/Light won't drop in the Dungeon at all. However, you should still be able to obtain Crimson Keys, as well as any drops inherent to the enemy types that you are killing.
 
Hey Darkstar01, fantastic writeup!

A quick question for you: you mentioned mob exceptions to the blanket biome spawning rules, and there seem to be other, pretty niche quirks as well. For example, I've heard anecdotally that for Chaos Elementals to spawn, the player cannot be standing in front of a player-placed wall.

Is there a place that has in-depth spawning info on mobs? The wiki just mentions the biome, but that alone doesn't mean much if you're trying to farm for a very specific set of mobs.
 
Hey Darkstar01, fantastic writeup!

A quick question for you: you mentioned mob exceptions to the blanket biome spawning rules, and there seem to be other, pretty niche quirks as well. For example, I've heard anecdotally that for Chaos Elementals to spawn, the player cannot be standing in front of a player-placed wall.

Is there a place that has in-depth spawning info on mobs? The wiki just mentions the biome, but that alone doesn't mean much if you're trying to farm for a very specific set of mobs.
I'm afraid that I don't know of any exhaustive lists. I have heard that enemies capable of passing through walls won't spawn if you're standing in front of player-placed walls, and my tests do seem to suggest this. Unfortunately, I don't have any hard data on it, nor do I know where to find any, assuming it even exists.

Most, if not all of the spawning information in the guide is stuff that I have personally tested, but in order to know all of the quirks with absolute certainty, you would probably need to look directly at the code. And I can't really help you there, I'm afraid...
 
Most, if not all of the spawning information in the guide is stuff that I have personally tested, but in order to know all of the quirks with absolute certainty, you would probably need to look directly at the code. And I can't really help you there, I'm afraid...

That's cool, you've already been extremely helpful. Just out of curiosity, what would you do to maximize the spawn of Chaos Elementals? I guess Hallow biome, pearlstone or similar spawning surface, cavern layer, and no walls? Anything else?
 
Creatures of the deep CAN spawn in the ocean.
Oh, yeah, I suppose that would make sense. Fortunately, they can't attack through walls, so that shouldn't impact the farm too much, other than them having more health (but slightly less defense, actually) compared to Arapaimas.
 
That's cool, you've already been extremely helpful. Just out of curiosity, what would you do to maximize the spawn of Chaos Elementals? I guess Hallow biome, pearlstone or similar spawning surface, cavern layer, and no walls? Anything else?
Well, technically speaking, you would also want a Water Candle nearby. You shouldn't actually need a Hallow biome if you use Pearlstone as a spawning surface, so you could place 80 Lihzahrd Bricks to increase the spawn rate further. Chaos Elementals will sometimes spawn on neutral surfaces (such as conveyor belts) if the biome is Hallow, but I don't know the exact spawn rate in either case.

The underground Hallow doesn't have many enemies to spawn, so one would think the spawn rate for Elementals would be relatively high. However, the wiki says "Underground Hallow does not suppress the spawn of other underground and cavern enemies", so perhaps using a Hallow biome with a neutral spawn surface to block out Illuminant enemies could actually lead to a higher overall spawn rate for Elementals. But I don't actually know. And of course if you used Lihzahrd Bricks to set the base spawn rate at Jungle, this wouldn't work, and you would need an actual Hallowed spawn surface.
 
Oh, yeah, I suppose that would make sense. Fortunately, they can't attack through walls, so that shouldn't impact the farm too much, other than them having more health (but slightly less defense, actually) compared to Arapaimas.


For what it's worth I haven't seen an Creature of the Deep when I was playing around with solar eclipse spawnrates during slime staff goldfarming. All the eclipse did was double the enemies on screen, but it was just Arapaimas and the odd jellyfish or shark.
 
Well, technically speaking, you would also want a Water Candle nearby. You shouldn't actually need a Hallow biome if you use Pearlstone as a spawning surface, so you could place 80 Lihzahrd Bricks to increase the spawn rate further. Chaos Elementals will sometimes spawn on neutral surfaces (such as conveyor belts) if the biome is Hallow, but I don't know the exact spawn rate in either case.

I got my Rod of Discord in the meantime. Built a quick teleporter farm; half an hour to build it, half an hour to grind. Lihzahrd bricks, water candle, hallow biome (I guess mixed with jungle) and pearlstone spawning surface. I killed about 130 elementals - about an even mix with illuminant bats & slimes, with the occasional flying sword thrown in. (Ok, maybe there were more slimes.) I also got a fair number of cavern skeletons, a few hallow mimics, and the jungle only contributed a few bats. Oh, and I saw exactly one miner, and exactly one nymph.

Funny thing was, with the hallow mimics teleported 1 block above me, they wouldn't do their usual "jump through blocks" shenanigans. Or maybe they died too fast (3 seconds or so) - but honestly I was worried about them a bit.
 
Oh, yeah, I suppose that would make sense. Fortunately, they can't attack through walls, so that shouldn't impact the farm too much, other than them having more health (but slightly less defense, actually) compared to Arapaimas.
Also, a great way to farm neptune shells!
 
Very nice write up man. You made it organized and easy to understand, thanks!

I have a question though and idk if you're still paying attention to this thread you started, but if anyone could help, i would appreciate it:
Regarding a NON-AFK arena to farm biome keys (all but hallowed).. To start with Crimson as an example, it seems to me that you would need to make sure there are 200 crimson blocks within a 50 tile radius (left/right) of wherever the player will be standing at any given time during farming. Being as you would be running around (not standing in 1 spot like an AFK farm) you would want to have all the biome blocks basically mixed proportionately spanning the length of the arena?

I haven't tested yet what kind of pattern would be needed/best to make that possible, but i wanted to ask for any insight on this. You did mention that with an active farm you may end up wanting/needing a bigger arena than you would have with an AFK farm. I've made quite a bit of online searches looking for designs others have came up with, but can only ever find AFK farms.

Also, i wanted to clarify; do "neutral blocks" (as a spawn surface), allow any enemy that doesn't require a specific biome block spawning surface, to spawn as long as enough biome blocks of their type are nearby?​
 
Regarding a NON-AFK arena to farm biome keys (all but hallowed).. To start with Crimson as an example, it seems to me that you would need to make sure there are 200 crimson blocks within a 50 tile radius (left/right) of wherever the player will be standing at any given time during farming.​
That's right.
Being as you would be running around (not standing in 1 spot like an AFK farm) you would want to have all the biome blocks basically mixed proportionately spanning the length of the arena?

I haven't tested yet what kind of pattern would be needed/best to make that possible, but i wanted to ask for any insight on this. You did mention that with an active farm you may end up wanting/needing a bigger arena than you would have with an AFK farm. I've made quite a bit of online searches looking for designs others have came up with, but can only ever find AFK farms.
I suspect that you're overthinking this. You don't really need a "pattern", per se. You could just have Crimson blocks a few tiles deep spanning the entire length of the farm, and then Corrupt blocks spanning a few tiles deep directly beneath those. There's no need to interlace different block types into any fancy patterns, or anything.

Two hundred blocks within fifty tiles to the left or right would only need two, maybe three tiles deep to activate the biome.

Also, i wanted to clarify; do "neutral blocks" (as a spawn surface), allow any enemy that doesn't require a specific biome block spawning surface, to spawn as long as enough biome blocks of their type are nearby?​
Well, that should be the case. I had jungle bats spawn on neutral surfaces while the jungle biome was active, for example, and certain Hallowed enemies (specifically Chaos Elementals and Enchanted Swords) seemed to spawn on neutral surfaces, as well. The problem with using neutral surfaces, though, is that in many biomes neutral enemies will also spawn on neutral surfaces, decreasing the de-facto spawn rate of non-neutral enemies. One exception that immediately comes to mind is the underground desert, since sandstone and hardened sand are already considered neutral, desert enemies will readily spawn on neutral surfaces so long as the desert backwall is present.
 

I suspect that you're overthinking this. You don't really need a "pattern", per se. You could just have Crimson blocks a few tiles deep spanning the entire length of the farm, and then Corrupt blocks spanning a few tiles deep directly beneath those. There's no need to interlace different block types into any fancy patterns, or anything.

Two hundred blocks within fifty tiles to the left or right would only need two, maybe three tiles deep to activate the biome.​

Hey thanks for the quick reply and detailed answers. The reason i thought i may have to interlace the different biome blocks together is so mobs that do require a certain biome block as a spawn surface, would be able to spawn anywhere since the available spawn boundaries would be moving around.
Although, i can't quite remember why I thought i'd need to worry about specific mobs being able to spawn as biome keys/pirate maps are biome based. Thinking of it now, I may want to use the arena for mob specific item drops also, if any. Either way, thanks again for the guide & answers!​
 
Nice guide!

I personally only use one mob farm. I just cut out a big rectangle in the cavern layer and build up so enemies don't spawn in the crags. I use this to get the metal detector from the nymph along with being very helpful for mimics for the star veil which makes the destroyer of worlds much easier. Then I just switch between corruption and hallow using the clentaminator to farm for the different souls. I can even get keys pretty easily using that one mob farm by just placing biome blocks nearby. Enemies spawn really fast. Fast enough to overwhelm me early hardmode.

The only other item in my opinion that is a pain to get that a mob farm might be good for is that dang Nazar from cursed skulls and possibly pirate maps considering getting the discount card and lucky coin items is a pain.
 
An effective farm using the arapaima method would which (in my opinion) is simpler is to build a big square/rectangle of lihizard bricks with the bottom dipping in the ocean, then you fill the top up with infected ice. Slope the bottom blocks so that all arapaimas are beneath you and place some platforms. lastly put some water buckets in your box so that you can breathe but still agro the arapaimas, summon you're minions, and go afk. For a farm while I'm online I would use @Darkstar01's first farm and use a weapon that can go through blocks (or 1 block wide walls like the vampire knives).
 
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