When this spell is cast, the magic-user causes a vertical iron wall to spring into being. Typically, this wall is used to seal off a passage or close a breach, for the wall inserts itself into any surrounding material if its area is sufficient to do so. The wall of iron is one quarter of an inch thick per level of experience of the spell caster. The magic-user is able to evoke an area of iron wall 15 square feet for each of his or her experience levels, so at 12th level a wall of iron 180 square feet in area can be created. If the wall is created in a location where it is not supported, it will fall and crush any creature beneath it. The wall is permanent, unless attacked by a dispel magic spell, but subject to all forces a normal iron wall is subject to, i.e. rust, perforation, etc. The material component of this spell is a small piece of sheet iron.