Zymbarak the Whispering Dead

Embodiment - {b} (If you pay the Embodiment
mana cost, this creature becomes target creature an opponent controls. At the end of the combat phase, the opponent must sacrifice that creature or be dealt 5 damage. You may pay the Embodiment cost at any time.)
When a creature an opponent controls enters the battlefield, that opponent must sacrifice that creature or pay {b}{b} and lose 2 life