Gemrazer (Promo Pack) [Ikoria: Lair of Behemoths Promos]

Mutate 1GG (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.)
Reach, trample
Whenever this creature mutates, destroy target artifact or enchantment an opponent controls.