Thorin's Masterpiece

When Thorin's masterpiece enters the battlefield, exile all nonlegendary permanents and all cards in all players' hands and graveyards. All players' life totals become the life total of the player with the lowest life total. All players may choose a card they own from outside the game or in exile and add it to their hand. All players then draw seven cards. {t}{1}{p/u}{p/u}{p/r}{p/r}: return a card from exile to the battlefield under your control. Thorin's Masterpiece doesn't untap during your next up