Fog Veil (Stronghold Augmentation)

Fog Veil: When creating this augmentation, choose one face of the wall. A 10-foot-thick cloud of mist extends out from this side of the wall. The fog obscures all sight, including darkvision, beyond 5 feet. A creature within 5 feet gets one-half concealment (20% miss chance for attacks). Creatures farther away have full concealment (50% miss chance, and sight can’t be used to locate the target).
The fog veil disperses in a moderate wind (11+ mph) in 4 rounds. A strong wind (21+ mph) has the same effect in a single round. Once the winds die down, however, the fog returns within 1d4 rounds.
Caster Level: 3rd; Prerequisites: Craft Wondrous Item, fog cloud; Market Price: 3,000 gp.