Agonizing Shock

You wreathe your hand in lightning before touching a creature, sending a wave of horrible electrical pain surging through their body. Choose one creature in range. They must make a Constitution saving throw, or take 4d8 lightning damage and be incapacitated for 1 minute, as their muscles and nerves are rocked with agonizing pain. At the end of each of their turns they can make another Constitution save, ending the effect on a success. As an action on your turn, you can send another surge through the creature affected by this, dealing an additional 2d8 lightning damage.