Terraria Calamity Death Mode "Triple" Brain of Cuthulu [Read Description for more info]
Very weird and broken, this was the only attempt where the brain didn't just fly away.
I'm using a mod called multispawn, which I have configured so it triples all enemies that spawn, so every time a Blue Slime spawns 3 of them spawn at the same time. This also works on bosses.
P.S. this mod can have some fun effects on bosses and enemies that have multiple segments or split up, since every segment or split is tripled, so you can end up with a Slime God fight with 108 Paladins (the slimes).
Put your thoughts and any questins in the comments, if something comes to mind.
Streamed at: / b0ne_r3aper