| Category | Strongholds |
| Continent | Karterus |
| Region | Ma'Ohari |
| Alias | Gu'sax 12 |
| Owner | Malshirk'iss |
| Built | 4 Lunar 9114 GE |
| Map | Tha'lith |
In the Tha'lith Conflict (9095 GE - 9289 GE), demons alongside thousands of Tragaran slaves built this imposing fortress. Graz'zt ordered Gu'sax 12, or Fort 12, built to threaten the lands around.
It had dozens of entrances. The main gate was at the head of defile running west, descending into the Gurutharni wetlands. In the Great Betrayal of 9343 GE, the Krotoan army was preparing to attack this place. They formed up in lines to go through Grazaghast, better known then as the Suicide Defile. Lukoon, recent escapee of Barhaz Halarax, arrived in time to halt the maneuver, saving them from what would have been a massacre on the tips of Mo'tzor's arrow demons.
In the Tilnangau-Varelay War, this place was captured by Varelay. It was renamed Mo'tzor in honor of Aperoq's most trusted chronicler; one who died for being a bit too truthful in his writings on his master.
In the Varelay Upheaval (2608 LE - 16 HE), the water table shifted giving birth to lake Styming. This submerged the defile, the main entrance and the lower levels of the fortress. An island fortress with submerged parts, it became the home of Vedrii and Yuan-ti.
When Malshirk'iss came to power, Mo'tzor was captured from a Rikhirra conclave. All killed, these naga were later raised, becoming Malshirk'iss's bone naga command staff.