Armor of the Grey Void

You touch a willing creature (possibly yourself), and a swirling grey mist surrounds it until the spell ends. The target's base AC becomes 15 + its Dexterity modifier. The mist counts as a melee weapon with the light and finesse properties. It deals 2d6+spellcasting ability necrotic damage and 2d6+spellcasting ability radiant damage on a hit. the spell lasts for as long the target can maintain concentration, up to 30 minutes.