The Brain of Cthulhu is a boss that was added in the 1.2 update. This boss is a replacement for the Eater Of Worlds if a world has The Crimson instead of The Corruption. The Brain of Cthulhu has the lowest HP of all bosses (besides King Slime). It is summoned by breaking every third Pulsating Heart, which is the Crimson counterpart to Shadow Orbs, or can be summoned using the Bloody Spine.
It is the second body part of Cthulhu to be put in the game, the first one being the Eye of Cthulhu.
It has two phases. In the first phase, it teleports around the player's vicinity, surrounded by eye-like enemies called Creepers, which randomly charge directly at the player. The Brain is completely invulnerable during this stage. Once all of the Creepers are gone, the front of the brain opens up, revealing a heart with an eye on it, as it enters stage two. The Brain's attack and speed dramatically increase at this point. Once all of the 1000 
have been exhausted, the Brain is defeated.
Note, the Brain can move through large blocks with ease and is quite large. If you are inside the small heart room (like to pick up the item said heart drops), the brain will spawn above you and trap you in the small enclosure. The brain will teleport down into the small room (even if the room is half its size) and can kill you very quickly. It might be a good idea to drop a bomb to blow up the third heart, then run to a clear open space to prevent getting trapped; at the very least, make sure you have your grappling hook ready or set up some platforms to quickly retreat to the main cavity. You'll need the extra room.
One interesting thing to note about the Brain is that it is the only boss in the game that does suffer from knockback during the second stage of the fight. Hitting it repeatedly will prevent it from reaching the player.
like the Eater of Worlds, the Brain of Cthulhu or his creepers will flee when out of the Crimson. (if not nearby 500 crimstone blocks)
Appearance[]
On its first form, the Brain of Cthulhu appears to be a giant brain with a small bit of a spine on the bottom with four tentacle-like nerves sprouting from the brain. On it's second form the Brain of Cthulhu has the front of the brain gone, showing a heart with an eye in it. Coincidentally, the heart in the Brain of Cthulhu looks like the Pulsing Hearts you need to break to summon it and the eye in the heart looks similar to the Creeper minions it has.
Strategy[]
Crimson hearts are floating red hearts found deep in the branches of the Crimson. A world with crimson features several different Crimson hearts and the items they possess are a crucial part to defeating the brain of Cthulhu.The Rotted Fork is a spear that drops from the Crimson heart, its useful against the Brain of Cthulhu with range, being long it can attack the boss from a safe distance.
A good idea is to make sure you spawn the Brain of Cthulhu in a spacious area, if needed destroy some of the blocks around you to create more space or find a spacious place in the cave you are in. You can also fill this spacious area with platforms to grapple onto, it is also a wise idea to put campfires on the platforms giving you the buff 'Slight increase in regeneration'.
Preparation[]
If you have a world with The Crimson, you should probably already have The Undertaker by the time you face him (breaking the Pulsating Hearts gets you this weapon, and it always drops from the first Heart you break). Stock up on bullets at least two hundred, to be safe.
If you have enough coins, the Minishark is also a wise investment, as it takes care of the Creepers fairly easily and during the 2nd phase of the battle, the knockback is enough to keep the Brain at a fair distance from you. Remember that the Minishark has a 33% chance not to consume ammo, so at least 800 bullets will do nicely.
If you have gone fishing in the Ocean, using the Sawtooth Shark will destroy him. Neither he nor the Creepers can even touch you, thanks to decent knockback and ability to be held down.
A magic weapon is extremely useful here, if not entirely necessary. You'll need to gather fallen stars to increase your maximum mana to around 100 or more before rushing into the battle. You'll also need silver armor (or equivalent) or better.
To make a good early magic weapon, hunt for 8 Gems of a single type and make yourself one of the staves (Topaz Staff, etc.; see Spells), depending on what metals are available in your world -- get the best one you can easily manage. This is the best weapon to use against the Brain at this stage of the game, due to it being able to pierce enemies and its low mana cost.
If you have broken a Pulsating Heart, chances are that a meteorite has landed in your world. Get the Space Gun with Meteorite Armor. As it will technically have unlimited ammo, can pierce and is extremely fast the Space Gun will effectively destroy the Creepers.
Build row upon row of platform in the large underground cavern in the Crimson. The staff and gun will help you fend off critters the happen across you while you're building. It will take 3-4 stacks of wood platforms to fill the space. Make them as far apart as you can reach without jumping; this ensures they're just close enough to reach with a single normal jump. You can place a platform every 2 blocks to save having to use more wood than necessary.
Due to it's powerful knockback, spread of fire and being relatively easy to create, the Molotov Cocktail can be devastating against both the brain and the creepers, especially when one remains unharmed against the flames caused by the weapon. Around 20-30 of them will do.
Swiftness Potions are useful in the battle as the extra speed will help you traverse the Platforms in the arena easily. Rocket Boots are good as well, and can be bought from the Goblin Tinkerer for only 5 
.
The Battle[]
Summon the boss either with the Bloody Spine or breaking Hearts with Bombs or a Hammer, so that you do not get trapped inside the Heart's cave by the Brain when it appears. Using a grappling hook to get out may also work but use bombs to be safe.
At the beginning, the Creepers will rush at you at first, simply avoid them and look for the main body of the boss. The Creepers always flock to wherever the boss teleports, so the easiest way to take them out is to aim straight at the main boss the whole time. This will also prevent Creepers from attacking you for the most part, as you're firing where most of them are and taking out more of them than you would be if you only attacked the ones that came close.
Blood Crawlers and Crimera will come at you occasionally, but they cannot go down through the platforms. Use this to trap them and kill them without getting in harm's way. Prior to defeating the WoF, none of the enemies here have ranged attacks, so you need only avoid running straight into them. As long as you're a few levels up on the platforms, the Face Monsters aren't any danger either. Just be wary that Blood Crawlers can climb on walls, and that if any spawn below you, they can easily make things harder. A good way to avoid this situation is to put solid blocks right under the lowest platform layers. This can also be ensured to catch any falling loot that go through the platforms.
Keep an uninterrupted barrage of magic and/or bullets between yourself and the main body of the Brain the whole time, and keep on the move so that he doesn't teleport directly on top of you. When you're out of mana, switch to the gun and just keep shooting until your mana recharges. You'll catch all the Creepers and most likely any other stray Crimson monsters in the crossfire.
When all the Creeper minions are dead and he's vulnerable, continue shooting him and keep moving. He is affected by knockback, and the knockback is the only thing preventing him outpacing you. The platforms give you sufficient mobility to evade him 80% of the time, so use them. Always switch back to the staff when your mana's fully recharged, because staffs tend to do more damage than the gun, and they can also hit multiple times with a single bolt if your aim's fairly decent. Although the projectile is slower than bullets, by this stage the Brain keeps quite close, so aim should not be a problem.
The platforms should catch most (if not all) of the Creepers' drops; wait until the boss is dead before you try to collect them all, to be on the safe side.
Another method is to set your spawn next the place at which you summon him and in the Crimson, because he teleports to you as long as you are within some distance of him and in crimson he will teleport to you. Let him kill you and then when you respawn he will teleport to you attack him or his creepers whichever stage he is on with your max DPS weapon. Once he dies, gather the drops and done, no potions necessary.
Farming[]
Farming the Brain of Cthulhu is great because it drops around 5 every time you kill it, and the item drops are worth anywhere from 11 25 
to 18 50 , which means more than 16 each time you kill the Brain. A good strategy for farming the Brain after you get the Bee Gun is to continuously use the gun. Around 400 
is all that is needed to demolish all of the Creepers and you probably won't need any Mana Potions or a Mana Flower as you can collect mana from the Creepers when they die. In the second stage, a Sunfury with armor penetration (available from the Sharpening Station) will kill the Brain in under 20 seconds. They are also a good source of Crimtane Ore and Tissue, meaning that it is possible to skip over the Eye of Cthulhu if you are looking for these materials, especially since the Eye despawns if the player dies, and the Brain does only if you get too far away.
Trivia[]
- Like the Eye of Cthulhu, the Brain of Cthulhu is inspired by HP Lovecraft's book, the Call of Cthulhu.
Bugs[]
- If you break 3 Pulsating Hearts, and then use a Bloody Spine, two bosses will spawn.
- Sometimes destroying only 2 Pulsating Hearts may summon the boss.
- Rarely, the Brain of Cthulhu will spawn without Creepers, making the fight impossible. (needs confirmation, possibly mobile only, also possibly multiplayer only)
Update Info[]
- Now drops the Brain of Cthulhu Mask.
- Added to the game.
Gallery[]
