Gix, Yawgmoth Praetor

Whenever a creature deals combat damage
to one of your opponents, its controller
may pay 1 life. If they do, they draw a card.
{4}{b}{b}{b}, Discard X cards: Exile the top
X cards of target opponent's library. You
may play lands and cast spells from among
cards exiled this way without paying their
mana costs.