Frostwall (Stronghold Augmentation)

Frostwall: A wall with this augmentation appears normal, though it is cold to the touch. If the wall is shattered or broken, anyone passing through the plane where the wall existed suffers damage as if it were a wall of ice (1d6+7 points of cold damage).
Caster Level: 7th; Prerequisites: Craft Wondrous Item, wall of ice; Market Price: 7,000 gp.