Skyreach Castle

Eons ago, cloud giants built this flying fortress to take their ancient battle against dragonkind into the skies. The spirit of a giant enables it to fly — this ancient bond dates back to the days when giants and dragons fought great wars. The binding kept dragons from taking these castles for their own, and the bond still holds centuries later.
The cult has struck a bargain with the castle’s owner, a cloud giant named Blagothkus who harbors no particular hatred of dragonkind (or anything else, for that matter). The spirit of his deceased wife, Esclarotta, controls the castle’s propulsion and buoyancy. The cult cannot afford to alienate Blagothkus, because the castle’s spirit will not obey them.
Skyreach Castle is carved from ice so thick as to be opaque. The ice is as strong and impenetrable as granite, thanks to ancient cloud giant wizardry. Towers and walls surround an iceberg core that’s been hollowed out to serve as the lair of a powerful white dragon allied with the cult. The whole thing can be hidden under a veil of fog and cloud, or set to move slowly with the wind.

Architecture

The castle is carved from opaque ice magically reinforced to be as hard as stone. While on the ground, the castle rests in a wide ravine on the outskirts of Parnast. All castle ceilings are 30 feet tall to accommodate the cloud giants who built it. All doors in the castle are made of 1-foot-thick ice as hard and tough as stone, but only half the weight. They are fitted with iron hinges and handles, and sized for giants. A normal door is 20 feet tall, 8 feet wide, and has its handles situated 10 feet above floor level.