Marit Lage, Stirring Oblivion

{u/b}{u/b}: Exile Marit Lage from your hand or the
command zone with 12 time counters At the
beginning of your upkeep, remove a time counter.
When the last is removed, cast it without paying
its mana cost.
Whenever a card is put into exile from anywhere,
for each card in exile, remove a time counter
from Marit Lage.
Marit Lage can't be countered.
When Marit Lage enters the battlefield, you win
the game.