Rivaz of the Claw is a rare Legendary Creature — Lizard Warlock card from Dominaria United Promos (PDMU), collector number 215p. Current market price: $2.24 (foil $2.98), TCGplayer market prices via Scryfall.
Menace {T}: Add two mana in any combination of colors. Spend this mana only to cast Dragon creature spells. Once during each of your turns, you may cast a Dragon creature spell from your graveyard. Whenever you cast a Dragon creature spell from your graveyard, it gains "When this creature dies, exile it."