Refering to the six subterranean battlegrounds introduced with the expansion Core Combat. Each cavern once rested beneath a continent on the main planet of Auraxis. After The Bending, these caves now exist in the cores of gigantic rogue asteroids.
The six caverns are Adlivun, Annwn, Byblos, Drugaskan, Hunhau, and Supai. Access to these caverns is controlled by surface links to Geowarps. Two caverns are open at any given time. A new carven opens every 3.5 hours, meaning each cavern is open for a total of 7 hours at a time.
Sometimes in Game Lore the caverns are referred to as the Auraxian Core.