Transformations

Isaac turns into his cat Guppy and gains the ability to fly. Every time you successfully hit with a tear, a blue fly will spawn (In Repentance this was nerfed to 50% of tears that hit).

Isaac turns into a human fly and gains the ability to fly. This transformation will turn most types of flies into friendly blue attack flies.

Isaac turns into his mother, giving him a knife which is attached to his butt and cannot be fired.

Isaac turns into a tentacled monster, gaining 2 black hearts and the ability to fly.

Isaac turns into a faceless angel, gaining 3 soul hearts and permanent flight.

Isaac turns into Bob (Sloth) and will now leave a trail of green poisonous creep as he walks.

Isaac turns into a living Mushroom and gains +1 HP.

Isaac grows two tumors on his face, which will fire diagonally in addition to Isaac's normal tears. This transformation is also a -0.3 damage down and -0.3 tears down.

Isaac turns into a buff berserker gaining +2 Damage, +0.15 Speed and spawns a random pill on the floor.

Isaac turns into a giant walking turd and he can now heal half a red heart each time a pile of poop is destroyed.

Picking up all 3 bum familiars will combine them and transform into SUPER BUM. Super Bum will pick up any of the other bum's pickups and drop double rewards.

Isaac gains a monocle and sometimes shoots 2 shots at once, similar to the 20/20 effect.

Isaac gains blue friendly attack spiders every time he takes damage and gains a permanent familiar spiderbro, which applies a random status effect to any enemies that touch it.

Isaac grows hair all over his face and gains +1 HP.

Isaac creates dust clouds when walking and has a chance to create rock waves around him after taking damage, which will spread outwards and damage enemies. (In Repentance this was buffed, you also can walk over rocks and destroy them)