Dark Cloak Lightless Slash

You brandish the weapon used in the spell’s casting and make a melee attack with it against one creature within 5 feet of you. On a hit, the target suffers the weapon attack’s normal effects and 1d12 extra Necrotic Damage 

This spell’s damage increases when you reach certain levels. At 5th level, the melee attack deals an extra 1d12 Necrotic damage to the target on a hit, and the damage the target takes  2d12. the damage rolls increase by 1d12 at 11th level and again at 17th level,