Acid Rain

With a gentle patter, corrosive raindrops build to an acidic deluge in a 60-foot tall, 30-foot radius cylinder, centred on a point within range. When the rain begins, each creature in the area must make a Dexterity saving throw, taking 4d6 acid damage on failure or half as much damage on a success. For the duration, each creature that starts its turn in the cylinder, moves into the cylinder for the first time on a turn, or ends its turn in the cylinder must make a Dexterity saving throw, taking 2d6 acid damage on a failure, or half as much damage on a success.