Out With the Old
Plane of Ash
One place of interest in the Plane of Ash is Fume, a fortress of ash and glass ruled by Ehkahk, the Smoldering Duke, an archomental of smoke and ash. Ehkahk often clashes with the itinerant Gazra, the Shifting Emperor, who disputes his claim of rule.
Optional Rue: The Great Conflagration
The collision of air and fire results in an endless windstorm. The wind and ash imposes disadvantage on Wisdom (Perception) checks that rely on hearing or sight as well as on ranged weapon attacks. The wind extinguishes all open flames and disperses fog and other clouds. A flying creature in the wind must land at the end of its turn or fall.
In addition, the whole field is filled with choking smoke, ash, and cinders. The smoke heavily obscures the whole area, and also makes it hard to breathe. Each minute spent in the smoke, a creature must succeed on a Constitution saving throw or be poisoned for one minute. If it fails its saving throw by 5 or more, it is also forced to hold its breath unable to breathe for that minute due to smoke inhalation (see Suffocating, PHB p.183). The DC for this savng throw starts at 10 and increased by 1 each minute. Creatures that do not breathe and creatures that are immune to poison damage or the poisoned condition automatically succeed on this saving throw, as do characters with their own air supply, and characters with appropriate protective gear have advantage on the save. Such characters do not have their save DCs increased.