Halt

Halt is a Watcher 0-cost common skill that gains 3 Block normally or 9 Block while in Calm stance. The Calm bonus makes Halt a conditionally powerful free card: when you're in Calm, it effectively provides 9 Block for nothing, which is excellent value. Outside of Calm, it gains only 3 Block for 0 energy, which is modest but still a free contribution each turn. The substantial gap between the two conditions means Halt is most valuable in decks that consistently enter and maintain Calm.

Halt is best in Calm-cycling builds that want to maximize the value of being in Calm stance. Entering Calm via Tranquility or Prostrate and then immediately playing Halt for 9 free Block before exiting Calm provides significant passive defense at no energy cost. Even out of Calm, having a free play in hand is useful for padding turns or triggering card count-based effects. Upgraded, Halt gains 5 Block normally or 12 Block in Calm, improving both values and making the Calm bonus even more substantial.