Thunder Strike

A beam of lightning streaks toward a creature within range. Make a ranged spell attack against the target. On a hit, the target takes 3d4 lightning damage. The creature needs to do a CON saving throw of 12, on fail it gets stunned.

The spell gets more damage when you reach higher levels: +1d4 at 5th level, +2d4 at 11th level, and +3d4 at 17th level.