Video Blindfolded FTW Master Mode Brain of Cthulhu + guide

[SorbetCafe]

The "guide" part of this is that the poisoned + on fire! debuffs make finding the real brain in the second phase very easy, which is the difficult part of the fight. Imps and hornets are the easiest way to achieve this and the auto-targeting makes the fight quite simple, but other options exist.

Also you could use actual weapons in addition to minions if the mood strikes you.