Trueshot Barrage

You fire an arc of golden energy in a direction you choose along a Line that is 240 feet long and 15 feet wide that originates from your location. Each creature in the Line makes a Dexterity saving throw, taking 4d6 Radiant damage on a failed save or half as much damage on a successful one. If the creature closet to you along this line fails its saving throw, then it takes an additional 4d6 Radiant damage.

Using a Higher-Level Spell Slot. Both the damage dealt along the line and the bonus damage to the closest creature increase by 1d6 for each spell slot level above 3.