Temporal Rift

At the beginning of each player's upkeep, that
player exiles a card from their hand. If that
player has no cards in hand, exiles two cards
from their graveyard. If that player has no cards
in their graveyard, exiles the top three cards of
their library. Then, if that player owns twenty
or more cards in exile, that player wins the game.
"And so it begins."
—Barrin, master wizard