Windmill Strike

Windmill Strike is a Watcher uncommon attack that Retains in hand, starts at 7 damage, and gains 4 more damage each turn it is Retained without being played. On the first turn drawn, it deals 7. If held for a second turn, it deals 11. Third turn: 15. Fourth: 19, and so on. The combination of Retain and scaling damage rewards patience, eventually turning into one of the highest damage single-target attacks available. In Wrath, each value is doubled: held 3 turns means 30 damage in Wrath.

Windmill Strike rewards holding it across multiple turns while playing other cards. In energy-positive Calm-cycling builds, you can afford to hold it while generating surplus resources, then unleash it in Wrath for enormous burst. The 2-energy cost is manageable, especially after several turns of Calm energy generation. The main risk is drawing it at a point where you must spend energy elsewhere or face an urgent threat. Upgraded, Windmill Strike starts at 10 damage and still gains 4 per Retain, making every turn it's held deal 10, 14, 18, 22... in base form.