Snapdax, Apex of the Hunt (Ikoria: Lair of Behemoths Promos 209p) - Planeswalker Stamped - Mythic

Mutate (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.)
Double strike
Whenever this creature mutates, it deals 4 damage to target creature or planeswalker an opponent controls and you gain 4 life.