SRD
3-level Evocation
A stroke of lightning forming a line of 100 feet long and 5 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 8d6 lightning damage on a failed save, or half as much damage on a successful one.
The lightning ignites flammable objects in the area that aren't being worn or carried.
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 above 3rd.
4th level: 9d6 lightning damage
5th level: 10d6 lightning damage
5th level: 10d6 lightning damage
6th level: 11d6 lightning damage
7th level: 12d6 lightning damage
8th level: 13d6 lightning damage
9th level: 14d6 lightning damage