Pain

Pain is a Curse card that is Unplayable and deals 1 damage to you each time you play another card while Pain is in your hand. The more cards you play in a turn, the more damage you take — a typical 5-card hand with Pain could result in 4 damage taken per turn just from normal play. Pain is particularly punishing for aggressive high-card-play decks, and synergizes awkwardly with Rupture (which converts HP loss from cards into Strength). It has no upgrade.