Could you add hints in the gallery? Since the game isn't very easy (not difficult but it's not the breeze through everything with one hand), randomly testing the monsters combination to see which one unlock a special animation can be quite frustrating.
Also, how the summoning tome work? On one floor, I summoned a succubus but on the next one I summoned a ghost.
Small question: do you plan meta progression or do you want to do a pure roguelike?
Also, you should make that you earn bits even if a follower/summon (or a monster) kill an enemy.