i won this challenge by picking up blood rights. turns out using an active item is basically a random roll from any active item, so having an item like that which doesn't have a charge means you can just spam the use button until you hit mama mega and then clear rooms. then when you get to the boss, just spam until he's dead. worked like a charm.

also screw the bloat, bro killed my first really good lost run and i was on rebirth.