The Reaper is a conceptual card placed at the bottom of a player's deck. If a player's deck runs out of cards and they draw the Reaper, they loses the match.
Some cards, like Spartacus and Treacherous Reversal, replace the Reaper with a Victory card, giving them a win when they run out of cards to draw.
Trivia[]
Despite the signifigance of the Reaper Card in gameplay, actual details about it are not covered by the rules.