Vigor

Vigor is a buff that causes your next Attack to deal additional damage equal to its stack count, after which all Vigor stacks are consumed. Unlike Strength, which permanently increases all Attack damage, Vigor is a one-time bonus that applies to the very next Attack card played. After triggering, Vigor resets to zero.

Vigor is most commonly found on The Watcher, with cards like Conclude and Pressure Points providing it. It is also obtainable from certain potions and relics. Because Vigor is consumed on the next Attack, it pairs best with high-damage single-hit Attacks to maximize the bonus. Vigor can be stacked from multiple sources before a big attack to produce burst damage. It does not persist between turns if not consumed — unused Vigor carries over until an Attack is played.