Wrath of The Draconic Lineage

You call upon your draconic based lineage and summon a large spectral dragon head for the duration of the spell. The head is that of an ancient blue dragon in form. The head is not solid so objects and people can pass through it. Once during the turn you summon the head and on every turn subsequently the head can make an attack. During the initial summoning the head breathes a 30ft cone of lightning and thunder, anyone within range must make a DEX saving throw or take 5d12 lightning damage and 5d12 thunder damage or half as much on a successful save. On subsequent turns, as a bonus action, you can have the head make biting attacks at anyone within 10ft of the head. Roll for a ranged spell attack, on hit the bite deals 4d6 magical piercing and 4d6 lightning damage. You can also move the head, as an action, to anywhere within another 120 feet of you during the duration. 
Upon either dispelling the head, losing concentration, or the duration runs out, the head bursts and anyone within 20ft must make a DEX saving throw or take 2d10 lightning and 2d10 thunder damaged and are stunned until the end of their next turn, or half as much on a successful save and are not stunned.