Hissing Chimera

Mutate {5}{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 from under it.)
When this creature mutates you may choose
target creature an opponent controls. If you do,
create a copy of that creature and mutate onto it.
{1}{u}: Return this creature to its owner's hand.