Kel'thuzad, Archlich

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