The Banshee is a ghost ship formerly commanded by the revenant, Gareth Narborel.
It is resistant to fire, cold, lightning, and acid damage.
The attuned captain/commander of the Banshee can create a 400-foot-radius sphere of fog centered around the skyship. The sphere spreads around corners, and its area is heavily obscured. It lasts for 1 hour, or until a powerful wind (at least 30 mph) disperses it.
Once the attuned creature uses this feature three times, they must complete a long rest before using it again. A long rest brings the possible uses back up to 3, but never over 3.