Lich's Duel Mastery is a rare Legendary Enchantment card from Mystery Booster 2 (MB2), collector number 546. Current market price: $0.27, TCGplayer market prices via Scryfall.
Hexproof When Lich's Duel Mastery enters the battlefield, exile the top five cards of your library face down as shields. If you would lose life, instead put one of your shields into your hand. If you can't, sacrifice Lich's Duel Mastery. When Lich's Duel Mastery leaves the battlefield, you lose the game.