In the jungles northeast of the Q’barran city of Newthrone is a House Jorasco enclave built on ancient ruins of uncertain origin. The halflings of the enclave maintain their distance from but are not overtly hostile to the dragonborn, the Cyran settlers, and the lizardfolk living nearby. They are cautious about unexpected visitors, however, because their enclave is built atop ancient ruins that contain powerful magic.
The Hall of a Thousand Mirrors is accurately named. Below the stone and wood of the enclave is a maze of corridors; a full-length mirror stands at each junction, making navigation difficult. For most, walking through the Hall of a Thousand Mirrors is merely unnerving. But those suffering from magical curses or madness find that the mirrors somehow display their afflictions—and then their nightmares walk out of the mirrors. If a cursed or maddened visitor can somehow fight off the images and walk through the Hall of a Thousand Mirrors, then the last mirror shows a normal reflection, and sanity and normal life return.
Source: Eberron Campaign Guide
Without the protection of the shared dreams of the lizardfolk, the dragonborn of Arkhosia had little protection against the corrupting power of Masvirik. Clan fought against clan, and those that opposed Masvirik had to focus nearly as much upon traitors within their own ranks as they did the armies of Rhashaak.
At first, the dragonborn would look at someone who fell to Masvirik’s influence and declare this a personal failing—the role that pride and dedication played in their psychology and culture would allow little else. Still, they recognized that the process was not instantaneous and that there was no shame in an individual strengthening their will against Masvirik’s influence. To this end, they built sanctuaries like the Hall of a Thousand Mirrors where those who showed signs of Masvirik’s influence were given support in fighting against it. The dragonborn have lost these facilities to history, but—if they were recovered—they could change the balance of power between the dragonborn clans and the Poison Dusk.
Recently, one of these facilities has been discovered by the softskins and now sits underneath a recently built House Jorasco enclave. The hall consists of a labyrinth full of magical mirrors. If someone who has been cursed or is under magical mental influence walks the labyrinth, they will be greeted by mirror images of themselves that have succumbed to their curse. These images can step out of the mirrors that create them and—if they are overcome—the person walking the maze can emerge free from whatever plagued them. House Jorasco is studying the strange magics in these mirrors while making use of them to help treat some of the most severe mental afflictions that they have been faced with.