Armor of Bones

Choose a pile of bones or a corpse of a Medium or Small humanoid or beast within range. While you are wearing no armor, the bones of the corpse forms into a suit of bone armor that instantly becomes donned and you are considered proficient with it until the spell ends.

You gain 13 temporary hit points and while you have these temporary hit points, your base AC becomes 13 + your spellcasting modifier and you gain vulnerability to bludgeoning damage.  The spell ends if you have 0 of these temporary hit points, doff the armor, or if you dismiss the spell as an action.  The bones disintegrate into ash whenever the spell ends.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, you may choose an additional two corpses or pile of bones of a Medium or Small humanoid or beast creature for each slot level above 3rd. For each corpse or pile of bones chosen this way, you gain an additional 13 temporary hit points.