Armor of the Lich

You surround yourself with the spectral visage of a lich. You gain 20 temporary hit points for the duration of the spell. While you have these hit points, you have a resistance to necrotic, bludgeoning, slashing, and piercing damage. You also cannot be affected by poison or disease while you have these hit points. When these hit points are depleted, the creature that depleted them takes 2d4 necrotic damage and the visage of the lich attacks the creature for assaulting its undead majesty.