Just as I wondered about alternative system for the freeform kind of magic of Mage, I suddenly find multiple alternatives! This is just as much a reminder and place holder for myself as it is a tips you you out there. Check out Clint Black's rules for improvised magic for Savage Worlds. They look quite usuable.
I guess Savage Worlds have a reputation for quite pulpy and cinematic action, but looking at how WoD games seems to be played I think it could fit. Personal horror or not, they can't get any less of that by Savaging them, in my opinion.