Ancient Silver Dragon is a mythic Creature — Elder Dragon card from Battle for Baldur's Gate Promos (PCLB), collector number 56s. Current market price: — (foil $99.93), TCGplayer market prices via Scryfall.
Flying Whenever this creature deals combat damage to a player, roll a d20. Draw cards equal to the result. You have no maximum hand size for the rest of the game.