Lich's Mastery is a rare Legendary Enchantment card from Dominaria (DOM), collector number 98. Current market price: $0.92 (foil $2.35), TCGplayer market prices via Scryfall.
Hexproof You can't lose the game. Whenever you gain life, draw that many cards. Whenever you lose life, for each 1 life you lost, exile a permanent you control or a card from your hand or graveyard. When Lich's Mastery leaves the battlefield, you lose the game.