Javelin of Lightning

When you hurl this javelin and speak "Gorm", it transforms into a bolt of lightning, forming a line 5 ft wide that extends out from you to a target within 120 ft. Each creature in the line excluding the target must make a DC 13 Dexterity save, taking 4d6 lightning damage on a fail, half as much damage on a success. The lightning bolt turns back into a javelin when it reaches the target. Make a ranged weapon attack against the target. On a hit, the target takes damage from the javelin + 4d6 lightning damag