Crackling Burst

You blast a creature or object with lightning which then arcs to a number of other targets up to your spellcasting ability modifier within 30 feet of the primary target. Each target must make a Dexterity saving throw taking 5d10 lighting damage on a failed save or half as much damage on a successful save. If the primary target is wearing heavy armor made primarily of metal (such as iron golem) then the secondary targets have disadvantage on their saving throws.