The Fireball Level Path Is a path of levels off from the Great Hall in Dark Castle, Color Dark Castle, and will show up in Return to Dark Castle. It consists of 3 levels : Trouble 1, Trouble 2, and Trouble 3.
The setting of of the Trouble Level Path takes you to the lower part of the castle, down to the bowels, where guards keep people from escaping, and prisoners get whipped by a Whip Henchman. It's the only level path, where you have to go back through the levels, after making it to the end.
Also if you fall in any pits through out the castle, they will take you to Trouble 3, the final level in this path.