Aniva, the Living Catacomb

Aniva, the Living Catacomb enters the battlefield
with X +1/+1 counters on it, where X is the total
number of creatures in your graveyard.
Whenever a nontoken creature you control dies,
put a +1/+1 counter on this card and create a 1/1
black Skeleton creature token.
When Aniva, the Living Catacomb dies create a
number of 1/1 black skeleton tokens equal to
it's power.