Lore of a Homebrew D&D Setting

The persistent storm clouds that churn on the horizon are accepted to be the source of the gloom that pervades this land, yet from my own studies there is little agreement upon their qualities, effects, or origin. I recently took it upon myself to seek out individuals who may have experience with this phenomenon, colloquially referred to as "Nocturnal Storms", to see if I could identify any consistent through-lines or trends in our current understanding.

To start, my own experience with such events is lacking, I should say thankfully, for they never appear to encroach upon the city of Vetrheim directly, always seeming to narrowly avoid it, or dissipate before they can pass over. The consequences of these storms do make their way to the city, one way or another, and this is what the local guard are often dispatched to take care of. For it's relative ease of access, and relevance, I thought I would start my investigation with them.

I was able to get in touch with a member of the Tempests through one of my own superiors, who had built a rapport with them during his own work. The Orcish officer was kind enough to accept my request for correspondence and interview, and as an experienced member of the force, I am pleased to have his insights. A rough transcription of our discussion of relevant subjects follows:

"What is your understanding of the Nocturnal Storms?" "Well, they've been a constant so long as I've been on the force, and for a long, long time before that. Depending on the time or day, they can be a little hard to spot on the horizon, but the clouds are always moving, churning, like... like milk that hasn't been stirred into a hot drink yet."

"Do they only appear during true night?" "Not necessarily, but something about the light certainly keeps them away, for what little of it the sky sees. Whenever its dark enough, they form, whether or not its truly night, but it's usually easier to make them out when it's not complete darkness out there."

"Can you describe what comes next?" "Right... the main reason the guard, the Tempests, even the Nightlord's... cavalry, any of us trouble ourselves with the storms. Wherever they gather, these horrible creatures emerge. I think the storms create them, but they also turn things that get caught in them into... abominations. You can recognise some of those creatures, the ones that are turned, I've seen cattle, wolves, people... but there are others that I am certain bear no relation to anything that belongs in this world."

"Those creatures.. the ones that can't be identified... what do they usually look like?" "They are.. singular, usually, I can't say I've seen any two that look alike. I can't say I've seen more than I count on both hands, though, which I'm thankful for. Generally, long, twisted appendages.. gnashing teeth, sometimes more than one mouth.. I'm never sure where their eyes are meant to be, if they have them, but you can tell that they see you."

"I see... thank you... What happens once these creatures are killed?" "They're destroyed, utterly. Anything that used to be living is putrefied by the 'corruption', and some old guard a long time ago found out that burying them all in one piece is a bad, bad idea. We burn them, and most things they touch, which I appreciate isn't exactly helpful for scholarly types like yourself, but I'm sure you understand."

"Yes, completely, I'm thankful to have you relaying all this, in lieu of gathering my own primary accounts."

I then broached the subject of having a documentarian along during the destruction of a 'nocturnal horde', a matter that I'm not sure my guest took entirely seriously, but he assured me that the matter of facing such creatures is often an unpredictable, and rapid, affair, and someone would have to be on-hand as presently as the Tempests themselves if they wished to capture any record of the occurrence.