Khus, Arena Champion

Mutate {u}{b}{g} (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.)
If this creature mutated, you may cast creatures
as if they had mutate (the mutate cost is that
cards mana cost.)
Whenever a creature you control mutates, put a
+1/+1 counter on target creature you control and
draw a card.