You create a 20-foot-radius sphere of mist centered on a point within range. The sphere spreads around corners, and its area is heavily obscured. It lasts for the duration or until a wind of moderate or greater speed (at least 10 miles per hour) disperses it.    If a creature within the mist takes lightning damage, the mist immediately disperses, ending this spell, and the lightning damage spreads to other creatures in the mist. Each creature within the mist, other than the creature that took the lightning damage, must make a Constitution saving throw, taking the same amount of lightning damage that the triggering creature took on a failed save, or half as much damage on a successful one.