Thor's Wrath

A swarm of lightning forming a line 120 feet long and 20 feet wide blasts out from you in a direction you choose. Each creature in the line must make a Dexterity saving throw. A creature takes 10d8 lightning damage on a failed save, or half as much damage on a successful one.
The caster can choose one creature within the range of the spell to be at disadvantage of the dexterity saving throw.The lightning ignites flammable objects in the area that are being worn or carried. 

At Higher Levels. When you cast this spell using a spell slot of 6th level or higher, the damage increases by 1d10 for each slot level above 5th.