The term is archaic, calling upon the ancient language of the magi, and those versed in the eldritch arts. In the more vulgar argot, terms such as scrying room and equally mundane names are bandied about. The fact that such limited terms are used to describe the proper mystic's psychomanteum demonstrates how little they actually know about what occurs within.
The follow string of Mirror-folk evolutions, Mihradhz, Mihrral, and Mihradamagus, are collectively known as The Mirr. They are all curious and slightly annoying, each in their own way. They advance through their lives by pestering the rare mortals who visit their plane.
In the harbour of a major city a large and terrifying ship made of human nails docks. Nobody seems to inhabit this ominous vessel, someone needs to go on board and unveil the mystery. In comes the PCs.