Bone Armor

If you are attacked by a melee attack, the attacker must roll a Dexterity save as the spinning bones may hinder the strike. If they fail the save, your Spellcasting Modifier (a minimum of +1) is added to your Armor Class for 1 round as the bones bolster the defense in the direction of the attack.

If you are still hit by a melee attack, reduce the damage taken by 2 per casting level. 

Bone Armor has 5 charges which are expended when it repels an attack. If cast at a higher level, add 1 more charge per casting level.