Yorick Idea

Souls of the Undead (passive): Yorick stacks a soul of the undead every 9/7/5 seconds, stacking up to 3/4/5 souls, these souls fill up his soul bar (like mana) that you can expend for what type of ghoul you want (Q,W,E,R)

I basically want souls to be his energy/mana bar that he can use to make what type of ghoul he wants. I want him to be able to control an army.

Of course changes will need to be made if this actually happens because I'm no gameplay artist, but I think this would be an interesting mechanic.