Thunder Cage

You throw a spherical net made of electricity at a target within range. The target must make a DC 18 Dexterity Saving Throw. The target takes 9d6 lightning damage on a failed save, and half of that damage on a successful save. If the target is Large or smaller and fails the saving throw, it also becomes restrained for the spells duration as the net grows to encase it. While restrained in this way, the target takes an additional 1d12 lightning damage at the start of each of his/her turn. The target can use it's action to make a DC 20 Strength Saving throw. On a success, the target is freed, and the spell ends. You can also end the spell with an action.