Unstable Hydra

At the beginning of your upkeep, put a +1/+1
counter on Unstable Hydra. Then, if it has +1/+1 counters greater than it's base power minus the
number of +1/+1 counters, destroy Unstable
Hydra and it does damage equal to the number of
+1/+1 counters on it to all creatures.
{x}{x}: Unstable Hydra gets X +1/0 counters.