YO! These are all EPIC and YES DO IT! I like the idea of the charmaria as you can have various traits so like if the Rat King fucks you more than the Toad King then you become more rat but any time you have multiple sources of dna you have those different traits. Maybe even give the player the choice of what to keep and what to loose. OH - You could have it as a need for the game to progress so like when the troll egg scene in the mine needs the PC to be x% troll or goblin to reach a certain achievement and the wizard in the forest can always revert you back to human form for a price! :P
Yeh Anthony's transformation could happen over a period of time after the troll caves. Like have Cryil's dad save the PC and have Anthony slowly transformation which is needed for a later achievement/progression. Like having the original guard *if in the sanctuary* leave your party and posses Anthony in his ape form lol. Should the choice to transform into an ape come from saving that one character in the stone forest as a sign of his gratitude?
I also like the rarity of Rohan's transformation idea. I think that is needed.... maybe it gets the PC to revert back to human form with the wizard? IDK.
The Pig transformation scene was hot as well so he can have a transformation aspect for the PC as well. the one that Rohan got stuck in the pod in the guard's room.