Charged Beam [Storm]

The power of the storm is in your hands, you focus it into a beam of energy directed at a single target.
Make a ranged spell attack against that target. On a hit, the target takes 2d6 Lightning + 1d6 thunder damage, then, if the target is large or smaller, they must make a Constitution saving throw against your spell DC. On a failed save, they take half the thunder damage and are knocked back 15 ft. On a successful save, they take full thunder damage and are not knocked back.