Nethroi, Apex of Death

Mutate {4}{g/w}{b}{b} (If you cast this spell for its mutate
cost, put it over or under target non-Human creature
you own.They mutate into the creature on top plus
all abilities from under it.)
Deathtouch, lifelink
Whenever this creature mutates, return any
number of target creature cards with total power
10 or less from your graveyard to the battlefield.