Island in the Mist
The Cassian Underground is the name given to the underground layers of Cassia.
- The top layer is a magically-powered sewer system built atop the ruins of an older, no-longer-operational layer of sewers. (17.5 mi diameter)
- The second layer is the Cassian World Well. (15 mi diamater)
- The third layer (which has no direct non-magical access to any of the above layers) is the Labyrinth Prison. (12 mi diamater)