Okay! Long over do, but here is what I am thinking for Rumpels powers:

Potions. Any potion you can think of to make. 
Spells. To summon things, trap things, or sometimes create things. No living thing can be made. These spells include enchantments and curses mostly. Long and short. One time use and permanent spells
Magical items. He has the natural ability to know how to use a magical item even if he has never seen it before. 

I want the theme of his powers to be something he has to work for. He has to create, learn, or find his magic. It's not just an ability he has. Make sense? Anything you think I should add or take away?