The Hell of Primal Shadows is an ancient plane, existing for eternities beyond measure. While not the original source, it has long since become the embodiment of true darkness. No night is quite so black as this, no absence of light so complete and pure; even in the darkest of our places, objects emit blackbody radiation of some kind. Such quantum rules do not apply here. There exists not a fragment of light within this blackest of hells.
Further, the shadows of this eternal midnight do not abide the encroachment of visibility. Sources of natural light do not work here: torches and lamps are rendered worthless; they still burn, their flames still consume, but they emit not a photon of light. Even magic is not immune to this; all but the most powerful of light spells will fizzle worthlessly, and even those that work are significantly reduced in effect and duration. It seems almost as if the darkness is actively destroying the light, a disturbing realization for those who're used to the idea of light banishing darkness with nary a struggle.
The denizens of the Primal Shadows are not demons in the traditional sense, focused on eternal torture and gleeful cruelty, though one could be forgiven for thinking such a thing. Each has it's own place within the brutal ecosystem that always seems to form within each of the myriad hells, an ecosystem to make the most horrific depths of the jungles pale in comparison. When mere humans are placed within it, they inevitably become prey to the vicious predators that comprise it.
Alas, eternity is truly circular in nature; any poor soul who becomes prey will reawaken within minutes of their 'death', with all the mind-searing memories of exactly how they died in screaming agony, knowing all the while that there is no safety in the unending darkness, and that within a very, very short time the process will repeat itself. Those souls doomed to spend their afterlife here quickly go mad from the constant terror and agony of being hunted and brutally eaten. All that is left are shallow husks of shivering fear and mindless horror.
The Bringers of Midnight
Dark, vast and terrible, the Bringers of Midnight rule over the Hell of Primal Shadows from their obsidian mountains. Incarnations of darkness itself, they are far beyond the ken of mortals. However, the limitless reaches of the countless hells still form a prison from which they cannot escape on their own. Thus do they extend their touch to the dreams and thoughts of mortals, subtly manipulating the course of events through cultic pawns, constantly striving to free themselves from the cosmic depths of their prison. Once they make good their escape, humanity shall witness an eternal midnight, an age of screaming madness and terror that even the gods of Light cannot stop.
In preparation for their escape, the Bringers of Midnight have altered significant portions of the ecology within their personal little hell, turning already-formidable creatures into nightmares of chaos and destruction. However, not everything of their origins was lost in these transformations. With few exceptions, the touch of light is anathema to the natives of this hell, searing flesh and burning away the darkness that comprises their very essence. Some, the most altered, those that are of more use than mere cannon fodder, are less affected by illumination, only beginning to suffer ill-effects after prolonged exposure to intense light.
Additional Ideas (15)
Fell creatures near the top of the food chain, shadowbeasts are a hairsbreadth away from being shadow incarnate. Their form is extremely fluid, shifting and changing as actual shadows do, becoming larger or smaller as needed. If seen with dim light (full daylight would annihilate it), it will appear as an amorphous mass of shadows, clinging to and creeping along the ground.
Cunning predators, they prefer to ambush their prey and drag it off into the darkness, enshrouding it with their caustic shadows before tearing it apart to release the essence of life within.
Like all creatures of this plane, light is a potent weapon against a shadowbeast. Enough light will kill it, as will sufficient application of magical damage. Physical weaponry, however, is next to useless in fending one off. Torchbearers should be cautious, however, for a shadowbeast will make it's first priority the removal of light and any who carry it.
The Onyx Serpent
A great creature of black, stony skin, whose slithering across the ground sounds like the grinding of mill stones. It has piercing eyes of gold and teeth that glow with a ghostly pale light, with a hiss that sounds like crumbling mountainsides. It's size belies it's speed, however, and this snake eshews venom, preferring instead to crush and swallow prey whole.
The hide is an organic obsidian composite harder than any known rock, easily capable of deflecting both blade and spell. Of the various fauna that exist in the Hell of Primal Shadows, this is the one that all others fear. You do not confront it, you sidestep it and pray it finds something tastier to go after.
The Ebony Octopus
It creeps from shadow to shadow, finding entry through the smallest of openings. Shadowy tendrils snake from around corners and beneath grates, grabbing ankles and dragging victims screaming into the darkness. What happens next is best left unsaid.
Notably, these tendrils seem immune to the normal corrosive effect of light upon the denizens of the Primal Shadows, retaining their form and power despite direct illumination. This makes them a huge threat against the unwary, who naturally assume that being in the light protects them from the dangers lurking in the lightless reaches. Only the core body itself is vulnerable to radiance, though trapping it long enough to fully destroy it is quite difficult; much like it's waterborn compatriot, the Ebony Octopus is hard to pin down.
Dog-sized creatures with thick, scaly skin, long claws and double-rows of razor teeth. They charge to bring down their prey, biting through calf or thigh with their terrifyingly strong jaws, though occasionally they'll hammer a large creature with their long tail to knock them over. Once their victims are downed, the creatures claw and bite without mercy, tearing out large chunks of sweet, delicious flesh to devour. Their bite is poisonous, quickly leading to paralysis and sepsis, presuming the prey lives that long.
The Dwellers In Darkness
The Wild Ones
The Night Hunt
The Hungry Maidens
Appearing as dog sized black widow spiders, they build black webs as stong as steel to trap the unwary, biting them with a paralysing bite, wrapping them up and sucking them dry.
Every ecosystem has its parasites; the Hell of Primal Shadows is no different.
Living, writhing shadows, Aphotic Worms clump together and swarm unsuspecting creatures, wriggling and sliding their way into any orifice they can. Once they've infested their target, they take full control over its actions, using their new host to hunt and kill prey. Non-sentient, the worms will flee a host when it has been rendered unconscious, immobile, or dead.
Their danger lies in numbers and hosts. The worms themselves are easily killed with the smallest of lights.