MTG - Ikoria: Lair of Behemoths - Migratory Greathorn

Mutate 2G (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.)
Whenever this creature mutates, search your library for a basic land card, put it onto the battlefield tapped, then shuffle your library.