Demonlord Jaarlkhan

Players can't gain life.
At the beginning of each players upkeep, that
player sacrifice a creature, if that player can't
they lose 2 life, and discard a card.
Undying (When this creature dies, if it had no
+1/+1 counters on it, return it to the battlefield under
its owner's control with a +1/+1 counter on it.)