Bolt Rail

You conjure forth a beam of electrical energy from your fingertips that flies out in a 5-foot-wide, 10-foot-long line in front of you. Each creature caught in the line must succeed on a Dexterity saving throw, or take 1d6 lightning damage.

This spells damage increases by 1d6 when you reach 5th level (2d6), 11th level (3d6), and 17th level (4d6).