You create a wall of whirling blades on a solid surface within range. You can make the wall up to 60 feet long, 20 feet high, and 1 foot thick, or a ringed wall up to 20 feet in diameter, 20 feet high, and 1 foot thick. The wall lasts for the duration. Enemies can attempt to fire missiles through the curtain of steel, but all creatures on the opposite side of the barrier enjoy a +4 bonus to their AC and a +2 bonus to saves made against attacks originating on the other side.

When the wall appears, each creature within its area must make a Dexterity saving throw. On a failed save, a creature takes 6d8 slashing damage, or half as much damage on a successful save.  Those passing through the blades suffer 3d8 points of slashing damage

At Higher Levels. When you cast this spell using a spell slot of 6th level or higher, the damage for both the dex save and passing through increases by 1d8 for each slot level above 5th.