Chaul'mur'ssin

Chaul'mur'ssin was a drow city in the Plane of Shadow.

History
It was founded by the former inhabitants of Chaulssin, a city in the Underdark of Toril. The citizens of the Chaulssin, called Chaulssinyr, followed the faith of Vhaeraun and refused to accept the one of Lolth for which the goddess decided to kill them at the hands of the armies of Menzoberranzan, in 734 DR. Vhaeraun gave the Chaulssinyr's leaders a warning about the impeding danger in the form of a shared dream and help to safely evade the army towards the Plane of Shadow.

The Chaulssinyr, already masters of planar magic, rapidly created several portals that allowed them safe travel to their destination and the entry of monsters into their city to cause massive harm to their enemies of Menzoberranzan.

Once in the Plane of Shadow, the Chaulssinyr had problems with monsters but not with an organised army, which allowed them to build the city Chaul'mur'ssin where their population thrived. Their success bought themselves the enmity of denizens of the Plane of Shadow, primarily of Clan Malaug on minor note with the Shadovar. They still wanted to eventually go back to Toril. The church of Vhaeraun expanded its influence over the years and had to abruptly take control of the city in 792 DR. They found out that the city's leadership was honeycombed with malaugrym who were all killed in a single day, though at heavy casualties among others the entire city's leadership. The church filled the void and to counter future incidents like that, they founded House Jaezred, an assassins' group and the forebears of the Jaezred Chaulssin, with the duty to find and kill shapeshifter spies. In the following years, the city fought with and learned from the malaugrym. The assassins of House Jaezred managed to get the game changer, the magic to split a zekyl's shadow dragon and drow heritage and turn the individual into a drow-dragon. The assassins got prestige and power but to prevent internal strife in the city, they decided to go back to Toril and start to actively destroy Lolth's matriarchy as the Jaezred Chaulssin in the city of Chaulssin.

Inhabitants
The denizens of Chaul'mur'ssin were generally drow, but differed from those found on Toril. They had a number of draconic features for being the descendants of Clan Jaezred, a shadow dragon clan that enslaved their ancestors and whom they have overthrown. They had zekylen and zar'ithra'rin among their numbers. Even most their drow population got after long exposure to the Plane of Shadow the characteristics of shadow creatures.

Other inhabitants of CHaul'mur'ssin were the Dark Bears. The Dark Bears were descendants of the quaggoths from their fallen realm of Ursadunthar. They were there as mercenaries and became characteristics of creatures of the Plane of Shadow.