Deal of a Lifetime

The next time target opponent would lose the
game this turn, instead that players life total
becomes 10, that player loses all poison counters,
and that player shuffles their hand and graveyard
into their library, then draws seven cards.
Remove all creatures attacking that player from
combat.
That player becomes your teammate. (A player
wins the game if their teammate wins the game, even
if they have already lost.)