Cloak of Iron

You cause those you choose to have their skin change to dense iron.

Choose up to 4 willing creatures within range (you can choose yourself). The skin of the creatures you choose is covered in a thin layer of iron, which grants them 10 temporary hit points. If damage reduces these temporary hit points to 0, shards of iron splinter off - all creatures within 5 ft. of the creature takes 10 piercing damage.

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, both the temporary hit points and the damage dealt increase by 10 per level of spell slot above 4th.