This article describes a custom creation, custom theme, or other fan material, made by a Brickipedia contributor. It has never been, is not, and will not be officially released.
The Dark Fortress is a set in Adventures of John and Jack
This set includes 13 minifigures and the Overlord Dragon. This Fortress turned from Garmatron from Overlords powers. It has 2 Fire catapults.
Fortress is appearing on Adventures of John and Jack but the chapter is unknown.