The Forever Night
A small shadow dimension full of horrors and home to a race of humanoids called Darklings. It is lit by constant, dim light from a single, massive moon and features bleak, stunted land choked with grey ash. The Forever Night is a fairly stable dimension that only rarely creates spontaneous portals to the "real" dimension and so far has caused very little problems for Earth. Some shadow creatures come from this dimension and afford darkness wielding sorcerers easily controllable minions. The energy from The Forever Night is easily tapped if a spell caster can get to it and can provide massive amounts of dark energy without attracting too much attention from its denizens.
The Forever Night was supposedly created by beings called the Lords of Primal Darkness, who are believed to be either powerful demons or some other kind of extradimensionals. They created the horrid landscape to their purpose and created the things on it to draw power from. The Darklings eventually rose up against their cruel and uncaring masters and the most powerful of their kind, the King of Secrets, somehow found or stole enough power to be able to cast the gods out. Wielding the Heartsflame, the power he had taken from them, he set out making the world more habitable and carving out a place for his subjects to live from the wilderness. This place became Volinstadt, the Dark City.
A sprawling city laid out according the the King of Secret's plans. It's constantly pushing against the wilderness and its soldiers and guards are constantly fighting to keep the outskirts protected. The city is the only major city in the Forever Night and features an odd design that is said to attract Heartsflame, the animating force of all Darklings to it. Without this Heartsflame, the city and the Darkling people would both be destroyed.
As the only major city in the dimension, Volinstadt tends to attract visitors from other planes interested either in power, minions or exotic plants and animals. It is a surprisingly civilized place in a hostile world and the inner city is usually quite busy.
This everburning fire was wielded by the Gods of Primal Darkness, a tool for shaping the world to their liking and giving life to their creations. When the gods were banished the King of Secrets stole a portion for himself to aid him in keeping his people alive and keeping their world from falling apart. He couldn't take all of this power into himself though, and it ended up scattered throughout the dangerous wilderness or buried within the landscape itself.
The King devised an effective and ingenius way of pulling the power in. He used his city as a focal point, a kind of mystic trap to bring the power to him. This power is used to safeguard the city and empower the Darkling people. Without access to Heartsflame, Darklings cannot live or even be born.
Aside from Volinstadt, the Forever Night is a terrible place. There are monstrous things created by the Gods of Primal Dark that lurk outside of the city, ready to devour anything that they can get their hands, pincers or claws on or rend them to pieces. These things are dangerous, constantly stalking the outside of the city and ready to cause havoc.
Some Darklings, especially those of the lowest tiers, choose to leave the protection of the city for the wilderness. It's assumed that they are quickly devoured or brutally slaughtered though there are rumors of renegades managing to survive on the outside.
Darklings and Caste
Darklings fall into several rigid tiers. There is no advancement from caste to caste and the only way to avoid this system is to escape into the wilderness of the Forever Night (an option that most Darklings avoid if possible due to the danger). The Darkling population seems to be linked to the size of the continually expanding Dark City, which in turn is linked to the amount of heartsflame available to give Darklings life. Because of this, the population doesn't increase or decrease much despite the many Darklings lost to combat with horrors in the wilds outside of the city.
-Belikashi (Tier 1): The lowest of the low. These Darklings are numerous and have a minor heartsflame that provides low levels of regeneration and enhanced strength. They posess very low intelligence and most end up doing menial labor or serving as shock troops against the horrors that dwell outside the sprawling Dark City.
-Garinkov (Tier 2): Enforcers and guards. Garinkov are instructed at the Academy of Martial Training and move on to guard high level spots in the city or go on to work for private employers in the third tier. Most Garinkov are incredibly strong and regenerate very quickly. Very few, Surova Grimwish included, have a powerful heartsflame that gives them additional powers and makes them highly sought after by tier 3 employers.
-Belikavi: (Tier 2): There is very little special about these Darklings. They tend to be smarter than their kin and have an aptitude for magic. They are often merchants and artisans in the Dark City and usually oversee Belikashi labor forces.
-Sulkovine: (Tier 3): Sulkovines are powerful, ruthless and possess varied magical abilities on top of their incredible strength and regenerative abilities. They are knights, in command of swarms of Belikashi soldiers and Garinkov sub-captains. They live for combat, even more so than Garinkov and though are not very bright they make up for it in aggression and tactical know how.
-Sulkoveshi (Tier 3): The idle nobles of the Darkling's society. Sulkoveshi are scheming, calculating and possess incredible magical aptitude. There have not been many Sulkoveshi created in the past several hundred years and they command great respect as architects of the Dark City and their mere presence attracts heartsflame from the wilderness to the city to create more Darklings.
-King of Secrets (Tier 4): There is only one Tier 4 Darkling known to exist. This being is the King of Secrets. He is never seen and the only information anyone gets from him is relayed through his tier 3 proxies. It is said that he controls the birthrate of new Darklings through his will and that the city is laid out according to his plans to attract heartsflame and improve the magical abilities of those that dwell within. Why or how he commands this level of control and how he became so powerful in the first place is unknown. At this point is is basically a demigod and causing trouble in his city is not advised.
Lords of Primal Darkness
The Lords of Primal Darkness are incredibly powerful beings, supposedly powerful enough to create and shape an entire dimensional plane to their liking. They were eventually expelled by the Darklings, who disliked their leadership and wanted to make their world more habitable. However, not all Darklings are happy with their new, castebound lives.
The Knights of the Nightmare are followers of the Lords. They work to bring them into power in whatever way they can. Many of their plots involve trying to summon the lords to a dimension they're not locked out of and working backwards. Unfortunately, one of the places they've chosen is Earth. The Knights work through human agents, searching for artifacts that were either stolen or taken by powerful spellcasters in the past or lost through portals to the world. They desire to plunge the world into eternal night, which will give their Lords either a new home or the boost they need to retake their old one.