With 11 transformations and 13 characters, it seemed reasonable to apply one transformation to each character as a good initiation into modding. I've tried my best to make these balanced and as not-OP as possible, however some transformations require strong items, or have strong effects in their own right which makes balancing tricky. As we cannot edit stats directly, the result is that most characters are a little stronger than in the standard game. If you want more of a challenge, show some restraint; do not take the first few devil deals and/or special item rooms. In the future I may create a "hard mode" version of this mod which nerfs special item rooms.

To get the most from this mod, you need all characters and items unlocked. Missing some items may mean some transformations do not work, and obviously you can't play as a character if you haven't unlocked them.

Characters
Mother (Isaac) [Mom's Bottle of Pills, Mom's Wig, Mom's Coin Purse x2]: Isaac always had to be mother. The wig is essential for the aesthetic, and mother pops pills like candy. This loadout allows you to get a headstart on determining the pill pool, for good or for ill.

Fun Guy (Magdalene) [God's Flesh, Mini Mush, Odd Mushroom (Thin)]: Maggy, but smaller and faster. Starts with 3 red hearts.

Bob (Cain) [Bob's Brain, Bob's Curse, Bob's Rotten Head]: Has 2 health, 5 bombs, and creep from the transformation.

Conjoined (Judas) [Brother Bobby, Sister Maggy, Headless baby]: Triple shot and some familiars. Strong, so you start with just one heart.

Super Bum (???) [All the bums]: Plays like the standard ???, except you have the option to trade in coins, keys and red hearts for stuff. Starts with one soul heart, which should quickly be offset by feeding Super Bum red hearts.

Guppy! (Eve) [Guppy's Hairball, Guppy's Collar, Guppy's Tail]: The Guppy transformation is very strong, so in the interests of balance some of the weaker Guppy items are used. Additionally, the character starts with only half a soul heart, and the character this is based on (Eve) has a weak base damage stat.

Beelzebub (Samson) [Jar of Flies, The Mulligan, Obsessed Fan]: A strong start given that typically many enemies in the beginning are flies.

Leviathan (Azazel): Basically Azazel on steroids, this character starts with a lot of damage ups. As a nerf, and to vary gameplay from standard Azazel, this character also starts with anti-gravity. Cumbersome but powerful.

Spun (Eden) [Experimental Treatment, Speed Ball, The Virus]: It's hard to make a character balanced when they get +2 damage from the transformation alone, the best I could do was minimise tears up and damage from the items. Given the random nature of Eden and Experimental Treatment, this character ranges from average to OP.

Seraphim (Lost) [Holy Mantle, The Halo, The Bible]: The Halo was necessary for the aesthetic, its strength in the early game is countered by the weakness of the final item, The Bible. Even as The Lost, Holy Mantle with an All Stats upgrade is absurdly strong.

Oh Crap (The Keeper) [The Poop, E Coli]: Pretty similar to the standard keeper. Heals for one coin every time a real poop is destroyed (poop created by "E Coli" is not considered real, poop created by "The Poop" is real), or if a coin is picked up as normal. Given that The Poop is more reliable than Wooden Nickel (100% chance to heal every room), this is a slight buff to The Keeper.

Because there are 13 characters and only 11 transformations, Lazarus and Lilith have no transformation. Instead, they have their own mini synergies. Lazarus has Tiny Planet + Soy Milk + Lost Contact, Lilith has Trinity Shield + Spear of Destiny.