This spell creates a spinning disk of razor-sharp blades.
These whirl and flash around a central point, creating an
immobile, circular barrier. Any creature passing through the
blade barrier takes 1d6 points of slashing damage per caster
level (maximum 20d6). The plane of rotation of the blades can be
horizontal, vertical, or slanted.
Creatures within the blade barrier when it is invoked take the
damage as well. They can negate the damage with a successful
Reflex saving throw, provided they can and do physically leave
the area of the blades by the shortest possible route. Once the
barrier is in place, anything entering or passing through the
blades automatically takes damage.
A blade barrier serves as one-half cover (+4 AC) for anyone