Corypheus, Lyrium Magister

When Corypheus, Lyrium Magister enters
the battlefield, if you haven't completed
Tomb of Annihilation, return Corypheus,
Lyrium Magister to its owner's hand and venture into the dungeon.
Whenever Corypheus, Lyrium Magister attacks, for each opponent, you create a
2/2 black Zombie creature token unless that
player sacrifices a creature.