Curse of the Undead

When Curse of the Undead enters the battlefield, put +1/+1 counters on creatures you control equal to the number of creatures in your graveyard.
{b},{b},{x}: Return target creature from your graveyard to the battlefield with mana cost X. It now has "If this creature were to die, exile it instead"
{u},{u}, {u}, {x}: You gain control of target creature with mana cost X until end of turn. That creature gains Haste. At the beginning of your next end step, exile it.
Whenever a creature you control dies, dea