Walking Beyond the Gate (3.5e Sacrifice)
From D&D Wiki
The undead are but living warped, souls who has passed through the gate, yet their gate continues to function, open, pulling energy to animate the body. With that the secrets of undeath are open, allowing you to duplicate the effects of Animate Dead. You may animate a body free of cost, but the body will only last 1 round/level before the gate, out of control, sucks the body dry as fuel and disintegrates the corpse.
Health Cost: -3 per HD of undead created.