Relkor, the Corpsecrafted

Whenever a creature dies, if Relkor, the Corpsecrafted is in your graveyard, put a corpse counter on Relkor.
At the beginning of your end step, if there are one or more corpse counters on Relkor, you may
return it from your graveyard to the battlefield
with X +1/+1 counters on it where X is equal to the number of corpse counters that were on it.