Lich's Mastery

Lich's Mastery
{3}{B}{B}{B}

Legendary Enchantment (CMC 6)
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.