Lord of the Void is a mythic Creature — Demon card from Ravnica Remastered (RVR), collector number 424. Current market price: $17.03 (foil $27.49), TCGplayer market prices via Scryfall.
Flying Whenever this creature deals combat damage to a player, exile the top seven cards of that player's library, then put a creature card from among them onto the battlefield under your control.