Revive in Debt

The next time target opponent would lose the game, they don't. Instead, that player's life total becomes ten, and they lose all of their poison counters. That player gets an emblem with "At the beginning of your upkeep, reveal your hand, and target opponent exiles a card from it. For as long as that card remains exiled, the chosen opponent may cast it, and spend mana as if it
were mana of any color to cast it.
"There, I saved you. Now... what can you do for me?"