Awaiting Death

Target opponent's life total becomes 0, and
their life total can't change for the rest of the
game. Then, exile this spell with 3 time
counters on it.
At the beginning of each of you upkeeps, if
Awaiting Death is exiled with a time counter
on it, remove a time counter from it.
For as long as Awaiting Death is exiled with
one or more time counters on it, you can't
win the game, and you opponents can't lose
the game.