Pain is a Curse.
While in hand, lose 1 HP when other cards are played, bypassing any Block. A deadly curse, even worse than Regret, as minimizing its damage is not often practical. This curse becomes a mixed blessing when used with self-harm cards including Rupture, Blood for Blood, Centennial Puzzle, Runic Cube and Self-Forming Clay.
Since the HP loss is dealt in increments of 1, it is completely negated by Tungsten Rod, however, if the player has any stacks of Buffer they will lose them, because Buffer triggers before Tungsten Rod.