Klauth, Unrivaled Ancient is a mythic Legendary Creature — Dragon card from Forgotten Realms Commander (AFC), collector number 50. Current market price: — (foil $11.42), TCGplayer market prices via Scryfall.
Flying, haste Whenever Klauth attacks, add X mana in any combination of colors, where X is the total power of attacking creatures. Spend this mana only to cast spells. Until end of turn, you don't lose this mana as steps and phases end.