How about a "new" creature for the game?

My suggestion would be the "Ashzie". This undead would be created by necromancers using the cremated ashes of the dead. It would appear as a humanoid shaped ash cloud that attacks by swarming its target, draining it of its HP while healing itself. And it would take full damage from Magical attacks against. Melee attacks would cause some damge to the victim of course, but won't do full damage to the Ashzie.

And if this were the tabletop game the Ashzie would have an even more insidious attack. Any living creature breathing in one mote of the creature would contract a disease that kills it within the number of rounds equal to its hit dice unless healing is done by a Cleric one level above the Necromancer who created it. The newly dead creature rises as a zombie the night it died unless it is cremated. If it was cremated it rises as a Ashzie that same night and can only be destroyed by a cleric who is one level or more higher than the Necromancer who created it. No ashzie would be created of the zombie were burnt to bits after its transformation though...