Brain of Cthulhu

" The  is a boss that was added in the 1.2 update.

It has two phases, and currently seems to resemble Ocram in how it behaves. It will teleport around the player during battle constantly, and it will spawn monsters called "Creepers" which must be destroyed before the boss itself can take any damage. It's behavior is very similar to the Eye of Cthulhu. It can be spawned by using a Bloody Spine or by breaking 3 pulsating hearts in The Crimson. It is about 5 time the width of the player.

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 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/set up some platforms to quickly retreat to the main cavity. You'll want the extra room.

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