How about make it so your Captain can be different classes instead of a swordsman to add stradgey maybe make it so you play the card to recruit your captian and he can be the class on that card and you can get cards to switch out for said captain
How about make the Doll's blood a object that can separately be changed in the skin menu, so you can have different dolls with different colors of blood
How about a power that makes a gray-scale clone of a object or a full gray-scale doll if it his the doll, and both objects, or dolls share health so if one dies the other does so
Perhaps add a stat to increase Magic in the game and make magic a stat in general, i dunno if the meter for magic increases but it would be a little helpful to have a way to increase it in some way, and have some weapons that make specific magic stronger