Brain Of Cthulhu

Info
The Brain Of Cthulhu (BoC) is Pre-Hardmode and the fourth easiest boss in terraria. He takes the form of a large brain, with four tentacles coming out the rear when he flies. In his second form, the two halves of The Brain open to reveal a heart inside, with a yellow ringed eye on it. The Brain has a number of Creeper s protecting it. These creepers look identical to the Brain's own eye, minus their bloodshot veins. The Brain seems to have a connection to the Eye Of Cthulhu, yet it does not have a Mechanical nor True counterpart. The Brain has one blue wire/vein coming off its heart, which could be it main power source.

The Brain Of Cthulhu (BoC) will attack the player in three main ways. In its first form, BoC will spawn up twenty creepers that surround and protect him. They have around one hundred HP in Normal Mode. While the creepers are about, The Brain becomes invincible to any attacks and starts to teleport right on top of you, much like King Slime (on Mobile, PC or Console). Once the Creepers are all dead, The Brain becomes vulnerable, and opens up its heart. Then it will proceed to ram the player aggressively, and then quickly running away. This will continue until the player dies, or BoC is defeated.

In order to summon the Brain Of Cthulhu, you must either break 3 Pulsating Hearts found deep in the crimson, or use a Bloody Spine (30 vile powder + 15 Vertebrates at a Crimson Altar). The Bloody Spine is recommended, as you may become trapped by the brain in the Crimson Caverns' tunnels. On the old Mobile edition, there was a rare bug that made the brain spawn without any Creepers and completely invulnerable if three Pulsating Hearts were smashed on Multiplayer Mode.

Strategies

 * If possible, always have a nearby house with a nurse and a dryad living there. The nurse can completely refill your health for a few silver coins, and the Dryad generates the 'Dryad's Blessing' buff which increases your defence. She also generates the Dryad's Bane debuff that negatively effects enemies, also make a long, flat arena, with heart lanterns, Campfires and Fireflies/Stars In Bottles.
 * When fighting Creepers or BoC, use weapons that inflict the On Fire! or Poisoned debuff, as both enemies are vulnerable to them. Fiery Greatsword, Imp Staff, Flaming Arrow and Flare are all examples of On Fire! Inflicting Pre-Hardmode weapons. Blade Of Grass, Thorn Chakram and Poisoned Knife are all examples of Poisoned inflicting Pre-Hardmode weapons.
 * Making extra floors above you using wooden platforms is useful for escaping BoC if you have not yet found access to rocket boot, or wings. Even better, place spiky balls on the platforms to harm incoming Creepers.
 * Melee weapons are highly recommended for Creepers and BoC. Using Ranged weapons would take extra long.
 * Use Hermes, Spectre or Lightning Boots to evade the Creepers as they move incredibly fast. If you can place Sunflowers nearby, they inflict the Happy! buff, which increases your movement speed (and monster spawnage).

Achievements and Usefulness
By defeating the Brain Of Cthulhu, you earn the achievement Mastermind.


 * The Brain Of Cthulhu drops Tissue Samples, which are incredibly useful because they can make the Deathbringer Pickaxe, the earliest obtainable pickaxe that can mine Hellstone and Meteorite.
 * The Brain also drops Crimtane Ore, which can be used to make the Blood Butcherer sword, one of the ingredients for The Night's Edge