You brandish the weapon used in the spell's casting and shoot a bolt of lightning into the sky. Lightning strikes the ground in a 20 feet long and 5 feet wide line starting 5 feet from you. All creatures standing in the area must make a Dexterity saving throw. On a failed save, they take 2d8 lightning damage and lose half their movement speed until the start of their next turn. On a success, they take only half the damage rolled and don’t lose any movement.