A freakin' witch with a bad @$$ fan for a shield and wand for a weapon would be nice... Or big old broom would do as well, hehehe!
He abilities would revolve around weakining enemies, draining mana (for a change, since the other drain-ers drain life), decreasing her cooldown, and a big fat nuke spell which takes like 3 seconds to cast and does insane single target damage.
Also, give her a passive skill that allows her attacks to bounce like good old chain lightning spells, and more passive skills to make her regular attacks interrupt enemy abilities for a fraction of a second... Up to a maximum of a full second at the highest level.