Terraria 1.3 Expert Brain of Cthulhu (Without explosives)
The brain of Cthulhu is still easier then the Eye to me... So if you keep killing yourself with explosives perhaps the mighty minishark is the ticket... Tips vvv
Keep your distance: Don't get close to the Brain or its creepers, the creepers will hit you several times causing major damage.
Don't be fooled: Although his new trick may seem dumb at first, at the end they are virtually identical, don't be afraid to use autopause and find out which one is him, I accidentally paused and decided to in the video.
Arena: Try to make your arena off the ground so he can't sit where you can't hit him, but unlike the EOC the BOC needs much less dodging room.
Weapons: Grenades work best on the creepers, dealing massive damage to high numbers, but watch yourself so you don't get hit, the minishark is a good weapon for the second phase.
Losing isn't the worst: Even if you only kill 1/2 the Creepers, you still get some tissue samples, thus you can upgrade your armor and do it again with superior armor!