Heh, so you've built an ocean grinder...
Underground! That's a fairly unique approach.
Obviously it's not going to be nearly as quick as something like Diceman's
Ultimate Hardmode Grinder, with rapid fire darts flying directly over the spawn surface. (Note you don't
need the minecart track in that design if you're only running it 'AFK' for a few minutes at a time, checking out a few web pages, etc, as you suggest in your video guide.) Or any design that doesn't require the mobs to travel to you to get killed. (Although having them come to you is a fair way to collect loot over longer AF periiods, of course.) e.g. my Turbo Truffle-worm farm (to self promote) or perhaps some other configuration of
vertical grinder/farm.
I'm not sure why you've half blocked off the air gap in the top left of the screen with tiers of greystone? They're spaced close enough to reduce the number of spawns on them (compared with those below), but the gap needs to be only 2 tiles tall to
block spawns. You could have just left this space open anyway, as the spawn events in that area would then just create water monsters below... Not sure if there are any other gaps in your build where mobs might spawn (and get stuck), but looks like you over-sized things (just from eye-balling you map). Did you check the
spawn box dimensions?
I don't notice you mentioned that you need 80 Lihzahrd temple blocks (or Jungle grass) to activate Jungle biome for the Arapaima to spawn...?
So how does this setup avoid spontaneous hardmode boss spawns? Just by being underground? (I've not noticed or looked into this problem personally.)
I like the use of the clemtaminator to change the biome blocks. And yes, it's 100 Pearlstone for souls of light, but 200 corrupt/crimson blocks for night souls (
artifical biomes guide). The count is within 49 tiles of player (number off top of my head, maye). Oh, to be precise, I figured it out before:
50 tiles right and left (of screen centre) and ~42 tiles up and down (it's a box shape, as usual).
Suggestion: you could dual purpose this kind of farm as a biome selectable fishing site. A simplified version of
this ultimate semi-autofarm, but with yours would have simple, manual biome selection, probably.
