Darkstar01
Official Terrarian

The title is supposed to be a quote from the merchant, but I had to put a space in '
h' because the censor was acting weird.

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=677299270
-The Eye of Cthulhu is often the first boss new players will face. While not the hardest of bosses, it can be a big surprise to the unprepared. This guide features a number of potential strategies for taking down the Eye, whether you want to take it down as early as possible, or are on expert mode and are just trying to get by-
Introduction
You feel an evil presence watching you...
With almost 3000 HP, the ability to pass through solid objects, complete and total immunity to knockback, and rapid minion summoning, the Eye may appear to be an overwhelming foe for beginners. However, it can be beaten even with no armor and a basic wood bow. Preparation is key, and can make the difference between the fight being hopeless (I'm looking at you, copper shortsword), and a total breeze. If playing on expert mode, you will experience this terror anew, so overpreparation is best.
If there are any items or concepts mentioned in this guide that you are not familiar with, you can look them up on the Terraria Wiki.
General Preparations
Unless you're speedrunning, there are a few easy ways to acquire weapons and items that you should try to get before challenging the Eye. If you're a new player, you'll probably want more than the minimum.
Bear in mind that the Eye will only spawn naturally when you have at least 200 HP and 10 defense, making this a decent litmus test of preparation for new players.
General Arena Setup
The Eye of Citulu is a rather predictable boss, with simple, well-defined attack patterns. This fact, combined with the relative lack of options in the early game, leads to a general one-size-fits-all arena for the Eye. This arena is also effective on expert mode.
The general idea is simply to give yourself room to maneuver, both horizontally and vertically. Horizontal room is created by laying out a long line of wood platforms a little ways off the ground. Having a lot of nice, flat terrain to walk across can make or break a battle until you gain advanced mobility enhancers. Vertical mobility is created by putting multiple rows of platforms down in this way, each directly above the previous one. These can be placed at jump height, but your vertical movement won't be as fast as if they were farther apart. By placing them farther apart, you can grapple to them for quick vertical movement. In this same vein, columns of wood platforms can be placed at regular intervals across each row, which you can grapple to, disengaging the grapple in mid-air to gain a speed boost. Even if you don't have a hook, you can jump on these vertical columns to reach higher levels.
The setup will look something like this:
The campfire will slightly boost your HP regen while nearby, and the presence of one or more sunflowers will increase your base movement speed by 18%. If you make your arena especially large, you may need multiple campfires. This arena is built over water for no particular reason; it would be better to build one over flat land, so the ground can be used for maneuvering.
It should be noted that this is a fairly basic setup; if you aren't skilled at dodging, adding additional rows of platforms and making the rows longer is advised.
If you are playing on expert mode, you will likely want to make your arena much longer than this, due to the Eye's increased speed during the final part of the battle.
General Defensive Strategy
Overview:
The relative dearth of options early in the game will prevent you from trying any gimmicky or overly clever strategies against the Eye. This fact, combined with the boss's predictable attack patterns, lends to a one-size-fits-all set of defensive tactics against the boss. The use of certain weapons may require modification of these tactics, which will be noted when these weapons are discussed.
Phase 1:
After summoning a few minions, the boss will lunge at you three times. Unless you are on a high platform, its first lunge will usually send it though the ground. For this reason, it is recommended to conduct the majority of the fight on one of the top rows, so that you can continue attacking it with ranged weapons at that point. On the top row of my test arena, the Eye just barely remained aboveground, and there was some empty space below the bottom row, so you'll likely need another row on top of that to prevent it from going under. If using a very tall arena, standing closer to the middle might be better, as it allows you to evade both up and down.
The boss will always attempt to lunge directly at you, but can only do so with very specific timing and distance. If you have good movement speed and a long arena, you may simply be able to run away from the boss without it catching you. If you lack either of these, try baiting the boss into lunging towards a position a bit off the ground. If you start running away immediately while it is under the ground, it will end up just barely aboveground, due to moving diagonally towards you. If you only move as it starts to lunge, however, it will go almost straight up, gaining more height. This way you can sneak under the eye between its second and third lunges, and even hit it with a melee weapon at that time, if you like. This is much easier if you retreat to one of the top rows of platforms in your arena, as you can fall through to the level below and sneak under it that way.
If you have a grappling hook, you can use it to grab the platforms above you to evade vertically, or to grab a column of platforms and quickly move yourself in that direction. If you disengage in mid-grapple, you'll instantly reach top speed with Hermes Boots. With a hook, there is more room for error when evading, due to it being generally faster than anything else at this point in the game. It may be difficult to simultaneously counterattack while firing a hook, however, so you will likely need to stop grappling to line up an attack.
Phase 2:
After falling below half health, the Eye will perform a grotesque transformation, revealing a toothy mouth. If playing on expert mode, the eye will also release a swarm of minions during this transformation. During phase two, the Eye will no longer summon minions, and will instead focus exclusively on ramming. It will attack more aggressively, so you'll need to either have good movement speed to outrun it, or strategic movements to bait it into missing you. Between sets of lunges, it stays closer to you than usual, leaving less time to react when it charges, but also making it easier to hit. Appropriately, it's attack power increases during the second phase, and its defense decreases. You may wish to drop to a lower row of platforms when you anticipate a lunge, as it may be difficult to move out of the way in time once it has actually begun charging.
On expert mode, the Eye will abruptly burst into a lunging frenzy when its HP drops below a certain amount. These frenzy attacks will become more and more frequent as its HP dwindles until it is charging non-stop while critically injured. The most reliable way to avoid this is with Hermes Boots, using a sideward grapple to pick up speed, but you'll need a long arena to avoid running out of real estate.
Barebones Battle (Advanced)
Overview:
Maybe you're speedrunning, maybe you're impatient, or maybe you just want to do it this way because you can. Defeating the Eye of Katholoo with minimal gear is entirely possible with enough skill, and a few key items.
Armaments:
The Battle:
If using a bow, you need simply walk away from the Eye while firing at it. Your movement speed will need to be above a certain minimum amount for you to actually outrun it, however. You also want to make sure the arena is long enough, so you don't go falling off a cliff or something. Going out on a limb and assuming your arena isn't long enough, you'll want to dodge around it in whatever way you can, taking advantage of the arena's multiple layers. Without mobility accessories, having those extra rows of platforms makes a big difference in your survivability.
If you have access to both Unholy and Frostburn Arrows, consider firing Unholy Arrows through the Eye's pupil during the first phase (to kill it's minions immediately), and then switching to Frostburn Arrows for the second phase. This can be achieved by placing Unholy Arrows in an ammo slot, but leaving Frostburn Arrows in your normal inventory, and then trading their positions when you want to switch arrow types.
Shurikens use a similar strategy, and since they can pierce they are useful during both phases of the fight. If thrown upward through the Eye, shurikens can potentially hit it multiple times. This means that you will want to stand still whenever the Eye isn't lunging, so that you can land as many vertical hits as possible. Even with no armor or potions, a skillful dodger can make short work of the Eye with these.
Slow and Steady (Beginner)
Overview:
You're probably new to Terraria, or maybe you're just a slow learner. Either way, somebody needs to justify the existence of pre-hardmode ore weapons and armor. It might as well be you.
Armaments:
Don't forget to bring potions. If you've found a mushroom biome, you can craft healing potions from two lesser healing potions and a glowing mushroom, which will restore 100 HP vs. 50 HP for the lesser potion. An ironskin potion will also have a potent effect for this stage of the game. If you're using a bow, an archery potion can also help.
The Battle:
If your arena is really long, you can simply run away from the Eye when it lunges. If not, you'll want to take advantage of the vertical space you have, dropping through platforms or jumping/grappling to higher ones as necessary.
Most of the weapons listed here pierce, so you can just shoot at the Eye's pupil to kill it's minions as they come without interrupting your attack. You'll want to toss throwing weapons straight up through the Eye, as they can sometimes hit it again when they fall down. The guns don't pierce (unless you're using Meteor Shot), but they should be fast enough to easily intercept the minions, anyway (though the musket might have some trouble).
Because the Eye loses defense during phase two, you could use a stronger weapon during the first phase, and then switch to a faster, weaker one (such as Minishark or Vilethorn) for the second part of the fight. Your first weapon will still need to be fast enough to deal with the minions, however. Saving the Minishark until phase two, when it will be most effective, can be a way to save on ammo while still burning through the harder part of the fight.
A spear or yo-yo could work, but acquiring a decent one of either may be impractical at this stage of the game.
What's that? I said there were a dearth of strategies, but there are a ton? Actually, almost all of these weapons use the same basic strategy: shoot the Eye in the pupil as it spawns minions, and dodge away while returning fire when it lunges. There are a surprising number of viable weapons, though. They're just not swords, and everybody's probably using a sword right now.
Armed to the Teeth (Expert Mode)
Overview:
A wooden bow just isn't going to cut it this time.
While you can beat the Eye with less than I recommend here, you're better safe than sorry when playing on expert.
Armaments:
There's no point in grinding early game ores for this encounter, so we're just going to skip them all. Get the demolitionist and buy some bombs and dynamite from him. Use the bombs to access a Shadow Orb/Crimson Heart and break it. Either do this between 12:00 and 4:30 am in-game, or wait until the following day for a meteorite to land. If you don't get one, break another Orb/Heart. The meteorite crash site can then be excavated with dynamite.
Hermes Boots or better are extremely helpful during this fight. By extension, you're going to want a lot of real estate for the battle, so be sure to make your arena extra long. Given how early this is in the game, and how expert mode increases the effect of defense, the warding modifier will be quite useful. A shackle is dirt cheap to reforge, but it might not be worth the money to reforge more expensive items, especially if you have a good reforge on your weapon. If you're desperate for extra defense, you could reforge a copper or tin watch, as they are very cheap. A white string is also a great candidate for cheaply acquiring the warding modifier. A silver of tungsten watch would be relatively cheap as well, though an aglet is similarly priced, and would at least provide a marginal combat benefit aside from the modifier.
The Battle:
Initially, you can treat this simply as the Aye of Kituwloo on steroids. It hits harder, lasts longer, and summons minions faster. This is nothing that your advanced gear won't be able to handle. When it enters its second phase, it will summon a swarm of minions, so be sure to take those out before continuing the fight.
Phase two will proceed relatively normally, until the Eye crosses below a certain HP threshold and unleashes its first frenzy attack. Try not to freak out too much. The only reliable way of avoiding this attack is to run, so you better have plenty of room. Acceleration is important; greater movement speed will enhance acceleration on Hermes Boots, but you can instantly jettison to top speed by grappling a column of platforms and releasing in mid-air. As the Eye's HP dwindles, its frenzies will last longer and longer until it never calms down. Make sure to stay on the upper levels of your arena, so you can shoot down at it as it comes out of the ground between sets of attacks. When it eventually charges non-stop, the frequency at which you take damage will be related to both the length of your arena (turning around = pain) and the speed with which you can end the fight.
When it goes berserk, try throwing grenades backwards (once you are sure there is some distance between you and the Eye). It is difficult to pin a hit on the Eye during its frenzy attacks, but it will almost inevitably run itself into your grenades due to the extremely wide sweep of its motions. Frantically chucking grenades at the end of the fight is a reliable way to strike the final blow (assuming you are moving across level terrain). Bear in mind that normal grenades pass through platforms, but sticky grenades will adhere to them. Throwing grenades directly downward may be more efficient than throwing them backward, if you don't have a clean shot, as the grenade may fly straight past the Eye while it is still belowground if you toss it backwards too far. If you use sticky grenades, however, it won't make much of a difference.
If you stack enough damage and fight aggressively, you can end the battle before things get ugly. Like its normal mode eyeteration (I'm sorry), this boss can seem impossible to those with ill-suited equipment. Using the gear recommended above, you can farm the expert mode Eye with relative ease once you get the hang of it. So long as you don't become complacent, your chances of victory will be quite good.
Aftermath
Ah, the satisfaction of a job well done. You beat that boss. Doesn't it feel good? What? You actually want stuff? Yeah, yeah, you'll get that too. The loot dropped by the Eye is as follows:
Demonite/Crimtane Ore:
Remember that special, glowing metal you found in that tiny patch that one time? (What? You don't? Please just play along...) This is that stuff. The only way to obtain Demonite and Crimtane Ore in bulk is by defeating bosses. And no, it isn't Crimitine Ore, it's pronounced Crimtane, you poor, sorry person (or maybe I'm just projecting?). The ore type that drops is the one that corresponds with your world's evil biome. You can use this to craft a sword, a bow, an axe, a fishing hook, a yo-yo, and (Crimson only) a flail. You can't craft armor, a pickaxe, or a hammer from it until beating another boss, however. If you have an excess of this and want to sell it, convert it to bar form first, as this will boost its overall value. In bar form, Demonite gives you 10 Silver 66 Copper per ore, and Crimtane gives you 13 Silver 33 Copper per ore. Yeah, Crimtane is worth more. Its bow, fishing rod, yo-yo, and flail (corruption flail is obtained from Shadow Orbs) are all inherently better than their Demonite counterparts, too. If it makes you feel any better, Corruption worlds get:
Unholy Arrows:
Maybe you already stocked some of these for the fight, or maybe you never plan on touching them. Either way, killing the Eye in a Corruption world grants you 20-49 free Unholy Arrows. These can hit multiple enemies, in case you forgot.
Corrupt/Crimson Seeds:
Do you want to embrace the dark side? Planting these seeds will create grass of their respective type, which will spread through adjacent grass. This can potentially be used to create an entirely new area of Corruption or Crimson, even in a world that does not naturally possess it. It could be useful to create a patch of artificial Corruption/Crimson in a remote area to farm their mushrooms, but beware of the new power afforded to these biomes in hardmode. If you don't properly contain it, then when hardmode begins, you may find your artificial biome spreading out of control.
Lesser Healing Potions:
Basic potions... yaaay? Boring but practical.
Trophy:
Every boss has a trophy, which has a 10% chance of dropping upon its defeat. You could hang it on the wall, sell it for 1 Gold, or hoard them in a treasure chest like the incurable pack rat you are! Or maybe I'm just projecting here... again.
Eye of Cthulhu Mask:
Do you like terrifying small children with the visage of a mutilated, toothy eyeball? Then you're a freak! But hey, who am I to stop you from living your dream? You'll need to kill the Eye an average of seven times before one of these drops (~14.3% chance).
Spelled? I spelled, what... oh snap! I mean, I of cilthoouoo, uh, thigh of clicluclu, lie uv thugleoguloglooo. Okay, I give up, you got me. I know how to spell it...
Binoculars:
Yes, you can get a pair of binoculars from this fight. You'd probably never know it if not for the wiki, though, since it's so rare. While holding them, you can move your screen view to a limited extent. They're slightly less rare on expert mode, but still very uncommon.
Shield of Cthulhu:
The expert mode exclusives start off strong with this wonderful item (I'm ignoring King Slime here). The Shield of Cthulhu is an accessory that allows you to dash to the left or right by double-tapping in that direction. Collision with an enemy will damage them, rather than you, and you'll recoil off. I still wouldn't recommend it as a primary means of attack, however. The true value of the dash is how it allows you to easily evade enemy attacks, dashing on the ground to instantly reach full speed with Hermes Boots, or even dashing in midair. The Shield additionally provides two points of defense. I held onto this until after Plantera, so any money spent reforging it will not go to waste.

NPC and NPC Goods:
After the Eye of Cthulhu is defeated, the Travelling Merchant adds the Code 1 yo-yo to his list of potential stock. If you haven't beaten any other eligible bosses yet, then defeating the Eye will allow the Dryad to move into any suitable housing. This grants access to a number of things, such as knowledge of the world's exact Corruption/Crimson percentages and the Dryad's Blessing buff, which boosts defense and life regen of allies, hurts enemies, and is projected in a field around the Dryad when enemies are nearby. The Dryad's stock includes pumpkin seeds, which can be used to grow pumpkins for armor (yes, armor. The set bonus boosts your damage) and pumpkin pie for a long-lasting well-fed buff, as well as Purification Powder, the only thing that can remove Corruption or Crimson from the land... for now.
Not to mention that the Eye of Cthulhu will stop harassing you if it was spawning naturally, but you probably already knew that.
Final Words
So, now you know how to kill the Eye of Cthulhu. We even know how to spell Cthulhu. But... I still don't know how to pronounce it! I read the creator's explanation of it, but I'm still confused: https://en.wikipedia.org/wiki/Cthulhu#Etymology.2C_spelling_and_pronunciation.
I guess we should just stick with the modern pronunciation, huh? You know, some things weren't meant for mortal minds and all that jazz.
VIDEO SUPPLEMENT :
Last edited: