Arkvold's Chain Tiger Lightning Bolt

Twin magical constructs resembling tigers of lightning blast forward a line 90 feet long and 10 feet wide in  direction you choose. Each creature in the line must make a Dexterity saving throw. A creature takes 8d6 lightning damage on a failed save, or half as much damage on a successful one. When a creature fails, the constructs split off towards two other targets, should another creature take damage im this way, they take 5d6 instead. This may occur only twice but cannot strike a creature already damaged by this spell. If there are no other creatures to target, the two constructs float nearby the caster. With an action, you may set them loose to continue jumping from different targets however no more than once. 

The lightning ignites flammable objects in the area that aren't being worn or carried. When creature fails with a critical failure, they are stunned until the start of your next turn.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d6 for each slot level above 3rd.