Tenten, Evolutionary Adept

Mutate {4}{u}{g} (If you cast this spell for it's 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.)
Trample
Whenever this creature mutates, you may cast a creature card from your hand without paying it's
mana cost. Then put three +1/+1 counters on
this creature.