Bone Armor

You use bones from corpse or willing undead (with bones) within 10 feet of you as a material for this armor. Create protective bone shell that surrounds target until the spell ends, granting him a +3 bonus to AC. This spell cannot cause the target’s AC to be higher than 20. The spell ends if spell AC bonus drops to 0 or concentration ends.

As a bonus action, the caster of this armor can detonate armor and remove 1 AC, from AC bonus. Each creature in a 10-foot-radius around the wearer must make a Dexterity saving throw. A target takes 2d8 piercing damage on a failed save, or half as much damage on a successful one.

Corpse or willing undead will be destroyed when creating this armor.

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, the damage increases by 1d8 and add + 1 AC for each slot level above 4rd.