Armor of Marrow

A suit of armor comprised of bony spines and skulls encases your body. For the duration, you gain the following effects: Your AC becomes 18 unless your AC is already higher. You become resistant to bludgeoning, piercing, and slashing damage from non magical sources. When you suffer damage from a melee attack, the target suffers 1d4 piercing damage.

At Higher Levels: When you cast this spell at level or higher, the damage is increased by 1d4 per level above 4th. Additionally, the AC granted by this spell is increased by 1 for every 2 levels above 4th.