Dark Bomb

You hold one of your hands back, concentrate a massive amount of void energy and release it as a 10ft orb of void energy. On hit, any creature that is within 30ft of the orb's impact must make a Dexterity saving throw. The creature takes 10d12 + 10 force damage on a failed save, or half as much damage on a successful one. After the main impact, a 20ft vortex of decaying void energy which lasts 3 rounds is created, making any creature that passes through the vortex take 6d8 acid damage. If a creature gets directly hit by the orb it wont be affected by the vortex on its next turn. Beyond that turn the creature is affected by the vortex