Basically these are voyages that are extremely difficult filled with chaos for both pve and pvp. These will not be balanced to crew size. To find these they would be on a board in any tavern.
Skull of siren lord: similar to skull of siren sing but instead u must head into a siren shrine to pieces of a compass that is guarded by a gorgon. And if u escape u will be attacked by a coral skelly galleon. It works similar to the barnacled dread where u must take out the armor first. This ship has two fragments and location of final fragment. Once the compass fragments are assembled it will lead u too the skull that causes similar properties of the Skull of siren song by beacon and slow ship.
Skeleton fort of hell: majes use of molten fortress: but no armies just all skeleton lords(ashen lords maybe) this one is wip.
Flamehearts Seafort: this will be similar to the dark fortress but will seaforts uses phantom balls on seafort and flamehearts ghost fleet. To gain access to the vault u will also face an ashen lord who has the key. It will be harder to get away from his attacks in smaller fighting area. Fort will also be covered in obsidian skellies.
