Lesson Learned

Lesson Learned is a Watcher rare attack that deals 10 damage and, if the target dies, upgrades a random card in your deck, then Exhausts. The kill condition makes Lesson Learned most valuable in non-boss fights where killing enemies is common. Each kill permanently upgrades a random card — in Act 2 non-elite fights, consistently getting kill upgrades over time significantly improves deck quality without needing to visit shops or upgrade campfire rooms. The Exhaust means it fires once per combat.

Lesson Learned is generated by Study (which top-decks one each turn) or obtained from Watcher rare rewards. In Wrath stance, the 10 damage doubles to 20, making kills far more likely on weakened enemies. The card's upgrade reward can target any card in your deck, including powerful but costly cards like Sands of Time or Signature Move. Upgraded, Lesson Learned deals 16 damage instead of 10 (or 32 in Wrath), making the kill threshold much easier to reach and the card far more reliable as a kill-confirm tool.