While you can’t lose the game, your opponents can still win the game if an effect says so.
2018-04-27
While you control Lich’s Mastery, your life total still changes. Lich’s Mastery’s effects don’t replace the life gain or life loss.
2018-04-27
You don’t have to exile all the cards from one place. For example, if a source deals 5 damage to you, you may exile one permanent, two cards from hand, and two cards from your graveyard.
2018-04-27
If you run out of other permanents, cards in hand, and cards in graveyard, you’ll have to exile Lich’s Mastery itself and lose the game.
2018-04-27
If you’re dealt more damage than you have cards to exile, you’ll just exile everything you can.
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.
