Zatio, Soaring Heartpiercer

Mutate {3}{b}{g}{u} (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 under it.)
Flying
Whenever this creature mutates, you may
destroy target creature an opponent controls
with power 3 or less. If you don't, draw a card.