Protean Hydra

Creature — Hydra

This creature enters with X +1/+1 counters on it.
If damage would be dealt to this creature, prevent that damage and remove that many +1/+1 counters from it.
Whenever a +1/+1 counter is removed from this creature, put two +1/+1 counters on it at the beginning of the next end step.0/0

Magic 2011
$2.00 HP Magic 2011 (Magic 2011 Core Set)