Sulumbra

Sulumbra is a large island that is perpetually smothered under a haze of necrotic energy. Most of Sulumbra is highly dangerous due to the large numbers of undead, but its great warded cities are famous for their size and wealth.

Sulumbra is also highly associated with Sellaire, who is confirmed to have inhabited the island when he was a mortal vampire of great power. Even after his ascending, the Mad King of the Undead's "children" still represent a potent threat to any who stray far from the guarded paths between cities.

Cities
Most of the non-undead inhabitants of Sulumbra live inside turning runes, a series of wards which prevent undead from entering the cities and streets of Sulumbra. Cities in Sulumbra are primarily magocracies ruled by powerful necromancers who are able to harness the island's undead into doing manual labor in huge farms and factories outside of the city.

Oldgate
Oldgate is a city of over 10,000 inhabitants, making it one of the largest cities in the prime material. The city is located at the crook of the Flowing Mist on the border of the Bloodmire. It is ruled by a group of powerful mages who animate the dead for free labor, leaving the living to devote themselves to other pursuits.

The city is famous for its enormous wall, which harnesses the power of the turning runes across the island to radiate a repelling effect so powerful that no undead could hope to breach it. The Shattered Conclave take their city's security very seriously: no undead are allowed inside, even when under the control of another necromancer. Some guilds have raised objections to these regulations, but the power of the Conclave is absolute.

The Shattered Conclave
The Conclave are the undisputed rulers of Oldgate. The group always consists of 7 powerful necromancers. The necromancers enact laws and live like kings in Oldgate; in exchange, they animate the dead outside the city to do labor and distribute the resulting crops to the city.

The Conclave is also in charge of maintaining the turning runes around the city wall. They tend to be highly paranoid about the threat of a powerful undead breaching the city and destroying them - in fact, the need for security is one of the few occasions where all members of the conclave are in complete agreement.

Crescent Hollow
Crescent Hollow is a town of around 2,000 that lies at the base of Sellaire's Jowl. The town is the subject of much superstition from the rest of the island, and its inhabitants are usually treated with some degree of distrust. It is certainly true that the people of Crescent Hollow incorporate the undead into their lifestyle more than others in the island - some even employ them as household servants.

The House Constantine
An order of loosely related good-aligned necromancers. They are famous for keeping the stronger undead away from the population centers and for being extremely eccentric. The duties of the members of the House Constantine consist mainly of patrolling the roads between cities, rescuing anyone who is attacked by undead, and heading off larger threats from outside before they can breach the turning runes.

Most members of the House Constantine live alone or with their family in small dwellings a little ways outside of large population centers. There will also usually be at least one member of the house within half an hour's walk of all settlements along the roads.

Geographical Features and Landmarks
The necromantic energy that permeates Sulumbra makes its presence known even in the landscape, which over the years have twisted into imposing and hostile shapes.

The Wraithwoods
The Wraithwoods are a haunted forest inside of which is hidden Murchenheim, the city of the undead ruled by the secretive fey called the Shaded Child. The woods are filled with specters and other undead, most of whom do not take kindly to the living.

Sellaire's Jowl
Sellaire's Jowl is a chain of mountains that separates the mainland from the domain of Donn,  The surviving lore claims that the Sanguine Fang, the mountain whose peak is the highest, was once the seat of Sellaire when he was the overlord of Sulumbra. The Sanguine Fang is still inhabited by a clan of vampires who claim to be descendants of the Mad King of the Undead.

Givosric
Givosric, also called the Patchwork Man, is the most powerful deity on Sulumbra. His influence is widespread, cults to Givosric are among the most dangerous threats to civilization on the island.

Givosric promotes the belief that undeath is a superior state of being to life. His followers are perform horrific rituals to transform themselves and any captives into twisted undead, usually ghouls, ghasts, or even wights in the most serious cases.