The Darke
Hellspawn
A formable, intelligent demon made up of thick black vapours. An immense burst of dark smoke that encases the land, usually it overtakes entire cities of demons in one swift movement. It is one entity/one giant soul, that has many different voices and personalities within it.
It's one core objective: to devour the souls in its wake.
It can form almost out of nothing, and takes cities by surprise at any given moment. There are seals on certain buildings within the cities that ward against this massive demon of blackness. When word gets out that The Darke approaches, demons will frantically flock to these 'safe havens', often there will be not enough room inside for everyone and it is a mad dash, every soul out for themselves before all safe havens are sealed up. The Darke can reside in a city for many days at a time, sometimes even up to an entire week in Hell (which is the span of a month in the human realm).
After The Darke has passed, demons will enter the city again and this is also quite the mad dash - as The Darke leaves behind the 'corpses' of the unfortunate souls who didn't make it to a Haven in time. Devouring and destroying the souls, into a 'permanent death' (their presence literally ceases to exist, and they become a blank staring corpse for the rest of eternity unable to move, speak, or do anything but look on into nothing as time passes).
These 'broken souls' are then used for various things, and sold in the markets as their empty carcasses are highly valuable for the creation of food, items, clothing, buildings, and pretty much anything and everything in Hell.
(Everything in Hell, right down to the grain of sand under your feet was once a living soul, broken and withered away to nothing with time.)
The Darke is feared if you have no shelter, but the carnage it leaves in its wake is actively sought after.
