You brandish the weapons used in the spell’s casting and make a melee attack with each against one creature within 5 feet of you. On a hit with the first attack, the target takes the attack’s normal damage and an additional 3d8 lightning damage, and the attack you make against the target with the second weapon gains advantage.   On a hit with the second attack, the target takes the attack’s normal damage and each creature other than you within 10 feet of the target must make a Constitution saving throw, taking 2d8 thunder damage on a failed save or half as much damage on a successful one. If the first attack reduces the target to 0 hit points, you can make this second attack against a different creature within 5 feet of you.