Necrotic Hydra

Wither (This deals damage to creatures in the
form of -1/-1 counters.)
If damage would be dealt to Necrotic Hydra
while it has a +1/+1 counter on it, prevent that
damage and remove a +1/+1 counter from
Necrotic Hydra.
Whenever a creature with a -1/-1 counter
dies put that many +1/+1 counters on Necrotic
Hydra