Acid Rain

With a gentle patter, corrosive raindrops build to an acidic deluge in a 60-foot tall, 20-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, the corrosive rain deals 4d6 acid damage to each creature that ends its turn within the cylinder.