Zakarum Undead

Lifelink, haunt (When this creature is put in the graveyard from play, remove it from the game haunting target creature)
When the creature Zakarum Undead is haunting enters an opponents graveyard, return Zakarum
Undead from exile and another target creature
from your graveyard to the battlefield. Target opponent sacrifices a permanent.
"Unrelenting evil." — Deckard Cain.