Umm... So, I perfected my Darkstorm Helmet a week ago, but I hadn't used the Call Lighting Storm since I had until today. I was speed blasting my way through the heroic Danger at Dunwater and I came to the Northern Barracks and thought, "Oh, I'll just let my artifact do the work here. It'd be entertaining!" But...

My Perfected Darkstorm Helmet's Call Lighting Storm is only doing 1 damage to mobs in a CR 5 quest.

EDIT: Just noticed there is no Caster Level below the spell. You can even see it on the image on the Wiki as well. Legendary DH has Caster Level 30, but Perfected DH has nothing written there.