Sukuna, the Disgraced One

Whenever Sukuna attacks an opponent, or whenever a player attacks you or a planeswalker you control, clash with that player. (Each clashing player reveals the top card of their library, then puts that card on the top or bottom. A player wins if their card had a higher mana value.)

Whenever you win a clash, search your library or graveyard for a shrine and put it onto the battlefield. Then you may cast a spell from your hand with mana value less than that shrine without paying its mana cost.