Cloud of Knives

You conjure a cloud of sharp knives around you.
The knives float in the air around your upper body, pointing in the direction you look.
Each round as a free action at the beginning of your turn, you can release one of these knives at any target within 30 feet that you can see.
This is a ranged attack that uses an attack bonus equal to your caster level + your key ability modifier.
Each successful hit deals 1d6 points of damage +1 per three caster levels (maximum +5) and threatens a critical hit on a roll of 19-20.
Damage reduction applies to knife attacks from this spell.
The knives are treated as magic for the purpose of overcoming damage reduction.
Material Component: A knife.
Optional Material Component:Using a silvered dagger (22 gp) in the casting of this spell allows the knives to overcome damage reduction as if they were both magic and silver, but the knives deal 1 less point of damage.