Lightning Bolt
A stroke of lightning forming a 100-foot-long, 5-foot-wide Line blasts out from you in a direction you choose. Each creature in the Line makes a Dexterity saving throw, taking 8d6 Lightning damage on a failed save or half as much damage on a successful one.
Using a Higher-Level Spell Slot. The damage increases by 1d6 for each spell slot level above 3.