Brain of Cthulhu Terraria boss · Pre-Hardmode · #4 in the usual order

Brain of Cthulhu in Terraria — Brain of Cthulhu

A giant floating brain that guards the Crimson, surrounded by a ring of eyeball Creepers. It is the Crimson version of the Eater of Worlds. It is the only source of Tissue Samples, used for the Deathbringer Pickaxe.

Stage: Pre-Hardmode
Required?: Needed to progress
Summon: Bloody Spine
Where: The Crimson, any time
Max life: 3,250 (Classic)
Defense: 14

Biome: The Crimson · Underground

Stats by difficulty

Stat	Classic	Expert	Master
Max life	3,250	5,525	7,029
Contact damage	30	54	81

How to summon Brain of Cthulhu

Bloody Spine. Use a Bloody Spine inside the Crimson, at any time. Craft it from 30 Vicious Powder and 15 Vertebrae at a Demon or Crimson Altar. Smashing three Crimson Hearts also summons it.

Attacks and phases

First phase: the Brain cannot be hurt. It teleports around you while 20 Creepers swirl in and attack.
Second phase (all Creepers dead): the Brain becomes vulnerable and rushes at you, teleporting often.
Expert: fake copies of the Brain appear in phase two, and contact can give you random debuffs.

Strategy

Clear out a flat area inside the Crimson before you start.
Use piercing or spread weapons to hit many Creepers at once in phase one.
In phase two, watch for the real Brain: the copies fade in and out, though in Expert they look more solid as the fight goes on.
Keep moving in one direction so its teleport rushes miss.
Stay inside the Crimson or the fight will end without loot.
Bring healing potions; the debuffs in Expert can stack up fast.

Recommended weapons

Melee

Blade of Grass or Blood Butcherer

Ranged

Minishark, or a bow with Jester's Arrows

Magic

Crimson Rod or a Ruby Staff

Summoner

Vampire Frog Staff with the Snapthorn

Armor and gear for each stage.

Drops

Item	Qty	Chance
Crimtane Ore	40–90	100%
Bone Rattle	1	5%
Lesser Healing Potion	5–15	100%
Brain of Cthulhu Mask	1	14.29%
Brain of Cthulhu Trophy	1	10%

Expert and Master Mode extras

Brain of Confusion Expert · 100%

Tissue Sample Expert · 100%

Brain in a Jar Master · 25%

Brain of Cthulhu Relic Master · 100%

Classic Mode rates. In Expert and Master Mode most loot comes in a treasure bag , which also holds the Expert-only Brain of Confusion.

After you beat Brain of Cthulhu

Tissue Samples and Crimtane Ore for the Deathbringer Pickaxe (needed to mine Hellstone) and Crimson armor
The Tavernkeep can arrive, which opens the Old One's Army event
Meteorites can start to fall

Did you know? Unlike the Eater of Worlds, it has no mechanical Hardmode version.

FAQ

How do you summon Brain of Cthulhu in Terraria?

Use a Bloody Spine inside the Crimson, at any time. Craft it from 30 Vicious Powder and 15 Vertebrae at a Demon or Crimson Altar. Smashing three Crimson Hearts also summons it.

How much health does Brain of Cthulhu have?

3,250 in Classic, 5,525 in Expert and 7,029 in Master Mode.

What does Brain of Cthulhu drop?

Crimtane Ore, Bone Rattle, Lesser Healing Potion, Brain of Cthulhu Mask, Brain of Cthulhu Trophy, plus the Brain of Confusion from the Expert Mode treasure bag.

What should I use against Brain of Cthulhu?

Melee: Blade of Grass or Blood Butcherer. Ranged: Minishark, or a bow with Jester's Arrows. Magic: Crimson Rod or a Ruby Staff. Summoner: Vampire Frog Staff with the Snapthorn.

Sources & picture credits

Guide text is original retrogameindex writing, checked against the Terraria Wiki. Boss statistics and drop rates are the game values shown in the Terraria Wiki’s infoboxes. Sprites and artwork © Re-Logic; local copies archived from Terraria Wiki file pages (listed on the image gallery).