Protean Hydra
{X}{G}
Creature -- Hydra
0/0
~this~ enters with X +1/+1 counters on it.
If damage would be dealt to ~this~, prevent that damage and remove that many +1/+1 counters from it.
Whenever a +1/+1 counter is removed from ~this~, put two +1/+1 counters on it at the beginning of the next end step.