Bruvac the Grandiloquent is a mythic Legendary Creature — Human Advisor card from Ravnica Remastered (RVR), collector number 418. Current market price: $43.73 (foil $50.71), TCGplayer market prices via Scryfall.
If an opponent would mill one or more cards, they mill twice that many cards instead. (To mill a card, a player puts the top card of their library into their graveyard.)