The Castlemark Tower in Final Fantasy XV has probably one the most confusing puzzles in the game and can easily be frustrating if you don’t know how the Castle mark Tower works. At the end of this dungeon in Final Fantasy XV, you will face the final boss and get the “Sword of the Tall” Royal Arm.

Final Fantasy XV

Final Fantasy XV guide for the “Castlemark Tower” Cube Room Puzzle

The Costlemark Tower dungeon appears impenetrable from the exterior during most times of the day. As the dungeon is inhabited by exclusively by demons, the entrance only becomes visible at night. Simply return at night and you’ll see the stairs have extended and the route through the entrance is now open.

When you enter the dungeon you have to make your way through the straightforward path (for the most part) and reach the main cube room, that has blue lights on the walls and floor.

MAIN CUBE ROOM: First, look at every cube in each corner and see which one you can interact with. (The cube in the South West is always the last and leads to the boss). In order to interact with the last cube SW, you have to make it through the other 3 cubes, that lead to increasingly difficult boss fights.

After Defeating the bosses for each cube, come back to the main cube room you started and find the next one you can interact with. FINAL CUBE IN THE SOUTHWEST: After completing all 3 cube puzzles and beating the bosses, you can interact with the last cube that leads to Jabberwock, an LVL 58 boss. After finishing him, you will get the Royal Arm “Sword of the Tall”.