Xanathar, Guild Kingpin (Ampersand Promo) [Dungeons & Dragons: Adventures in the Forgotten Realms Promos]Set: Dungeons & Dragons: Adventures in the Forgotten Realms Promos Type: Legendary Creature Beholder Rarity: Mythic Cost: {4}{U}{B} At the beginning of your upkeep, choose target opponent. Until end of turn, that player cant cast spells, you may look at the top card of their library any time, you may play the top card of their library, and you may spend mana as though it were mana of any color to cast spells this way.