Potion uncommon
This bottle has a small amount of clear water at its base and has a thick cloud of vapor at its top, which constantly rains small droplets of water. If you open this bottle, the cloud inside launches out of the bottle and expands rapidly to fill the sky in a 100 foot radius. The cloud then releases a torrential wave of heavy rain on the area below it, filling the area with 2 inches of rain instantly before fading away.
If the area is enclosed and smaller than the 100 foot radius, such as a building or a cave, the cloud will fill the area in a condensed form, raining a proportional amount in the area (for example, 50 foot radius is 4 inches of rain, 12 foot radius 16 inches of rain, and 6 feet would be 32 inches of rain). This condense rainfall makes the area difficult terrain for non-amphibious creatures.
All magical and non-magical fire within the area is instantly extinguished, and all fire elementals in the area must make a DC12 Constitution saving throw, taking 2d10 cold damage on a failed save, or half as much on a successful one.