Goregora, Queen of Doom

Whenever an Hydra you control other than
Goregora, Queen of Doom dies, create X 2/2
Demon tokens, where X is its power.
Whenever Goregora, Queen of Doom leaves the
battlefield, destroy all Demons, then return
target Hydra from your graveyard the battlefield
with X +1/+1 counters on it, where X is the
number of Demons that died this way.