Descent of Endless Thirst

At the beginning of your upkeep, sacrifice a
creature. Put X +1/+1 counters on Descent of
Endless Thirst where X is that creature's power.
If you can't sacrifice a creature, destroy Descent
of Endless Thirst.
When Descent of Endless Thirst dies create a
black 1/1 leach creature token for each +1/+1
counter on Descent of Endless Thirst.