Dragon's Breath

Those who navigate the water of the dragon's bay, find their view of the horizon broken by an endless column of jet-black smoke rising from beneath the ocean. Hidden under the rolling waves is the monstrous volcano named Dragon's breath, which fills the surrounding waters with murky soot, toxic fumes, and boiling heat.
Elemental energy swirls around this ominous peak, leading many experts to believe that a rift to the Elemental Plane of Fire might sit at its heart. Natural creatures of the deep have been slowly twisted into fiery mockeries of their original selves, and regular tremors suggest that the mountain may be growing.

Features

Flame Storm. Sooty thunderclouds shot through with red and orange lightning release a deluge of fiery droplets. Any creature caught in the burning rain takes 2d6 fire damage at the start of each of its turns. The droplets ignite any flammable objects that aren’t being worn or carried; otherwise, the droplets burn out immediately. The smoke, soot, crackle, and low roar of the storm impose disadvantage on Wisdom (Perception) checks and ranged attack rolls. A flame storm usually lasts 2d4 minutes, though the originating storm clouds can persist for days, creating multiple flame storms.

Type

Volcano