[dataweaver]

It's doable. Realm Magic was based off of the magic system from Mage: the Ascension, which had a group of mages who practice Voodoo. So take a hint from Mage: in that game, you get a given style of magic as much by how it's done as by what you can do. In effect, bring in the magical modifiers from Path Magic — Sacred Space, Ritual Time, and material components — and let them provide bonuses to the Voudoun practitioner when he works then into what he's doing.

As for what he can do, look at the Paths from the original Voodoo: the Shadow War and try to match them up with your Realms. IIRC, there were Dreams, Health, Luck, Protection, and Spirits. Spirits translates directly; Dreams is probably a subset of Mind. How do your other mages heal? Through a subset of Matter, I'm guessing? Luck and Protection are the tricky ones, as they tend to correspond more with what you do than what you're affecting: Luck is a sort of across-the-board “nudge it” effect, while Protection is a similarly across-the-board “protect it” effect.

Also, I'm guessing that you demand Space for “voodoo dolls”. I'd recommend that Voodoo use a subset of that which focuses exclusively on Sympathetic connections: you can't use it to warp space or teleport, but you can sense and manipulate the bonds between the subject and people, places, or things that are important to him.