Moving castle
Dark elves from menzoberranzan that have a castle that can teleport would be pretty neat. Quite similar to the vampire stuff from castlevania, but then being dark elves would be just the right amount of different. It wouldn’t be able to house a crazy huge army. Maybe like 500 soldiers + the royal family. Also maybe the mechanism being able to amplify any area spelll could be interesting but will need to think about with what, could be used in a way that’s too busted. But players finding it and using it to blow the whole place up would be pretty cool. There could be a progression to how the castle moves.
- levitate
- Fly
- Teleport
- Planeshift
This progression in technology could be interesting not just for this castle but in being able to add it to other things.