Doom Castle

Doom Castle is a location from Final Fantasy Mystic Quest. It is built into the architecture of the Focus Tower, with the basement of the Castle built underground in the plateau the Focus Tower is on, and the rest of the castle extending to the top of the tower. Given that the Focus Tower possesses no visible distinction on the overworld map where the Focus Tower ends and Doom Castle begins, it is possible that Doom Castle's upper floors exist in an alternate dimension which is grounded in the Focus Tower. This is supported by the variety of architecture the upper floors possess, as well as the room the Dark King is in.

The basement of the tower is a sand-filled pit similar to the Bone Dungeon guarded by the Skullrus Rex. The staircase behind Skullrus Rex leads into a closed-off area of the Focus Tower before leading back into the castle. The second floor is an icy area reminiscent of the Ice Pyramid and is guarded by the Stone Golem. The third floor is based on the Lava Dome's inner chamber and contains the Twinhead Wyvern. The fourth floor is based on Pazuzu's Tower and is guarded by Zuh. The fifth floor contains a statue of Benjamin and four chests containing copious amounts of healing items. Afterwards, the castle's summit houses the throne of the Dark King.