[LadyLightning]

Why not just give the owner of a key the ability to destroy the dungeon they've created, but only if the core has been acquired?
Any players remaining in the dungeon would be shunted back to the world map. Then the key owner could just create a new
one wherever.

Yes, there will be those assholes that create a dungeon and close it right after they've cleared it, regardless of who else may be
trying to have fun in it. But I imagine there will also be plenty of people who leave it open, too.

Then again, I also believe that a dungeon's banner text should show the number of players currently inside it, the number of
~parties~ those players have made, and the currently-displayed name and/or alias of the character who created the dungeon,
if any. If not, it should be flagged 'random.'