Festering Hydra

Trample
Amalgamation (When this creature enters the battlefield, you may exile any number of creatures
from your graveyard, this creature enters the battlefield
with that many +1/+1 counters on it.)
Festering Hydra enters the battlefield with X
+1/+1 counters on it.
{r}{r}{r}: Festering Hydra deals X damage to any
target where X is equal to the number of +1/+1
counters on Festering Hydra.