The idea of this dungeon is that it was created after the fall of Tar-Baphon to house a corrupted artifact formerly known as Sunlight and redubbed Nightfire post corruption. I altered the Mace of Pharasma to hold the soul of a former high cleric of Pharasma. The cleric who now inhabits the Mace had a younger brother who was a Paladin of Sarenrae whose soul was also placed inside of the Scimitar he weilded in life. Both of these people in life were pure of heart and fought together against all that was undead and evil and continued to do so for generations through others who wielded them.
During the Tyrants rule, Sunlight was stolen by one of his generals and was slowly corrupted over the years becoming Nightfire. I made it so that the Mace of Pharasma was lost when this general faced off against the current weilder of the Mace. The two weapons/brothers collided and fought a mental war and the Mace went soring to the heavens (not to be seen again until as planned in the AP) losing the unseen battle and leaving it's weilder to be struck down.
Later, after sealing the Tyrant under Gallowspire, the nights of Ozem and Sarenrae hunted the former general, defeated him and retook Nightfire/Sunlight. They tried to cleanse the blade, but all efforts failed as the blade slowly corrupted all that would try to use it. After years of trying, and discovering that it was indestructable, the same mages/clerics that created the great seal, created a dungeon to house Nightfire. They then teleported the entire dungeon inside a mountain of unknown location.
My players recently put together many clues to pinpoint this dungeon and have need of the knowledge Nightfire posses about who the heir of Tar-Baphon is. Currently the Mace is not conscious and has not spoke to the players and will not unless it and it's brother are brought together again in battle. Over the years Nightfire has worked it's corruption onto it's protectors and now works with them to find a way to escape. This dungeon cannot be teleported into or out of and has only one entrance which can only be opened from the outside and my players are about open this entrance. They must defeat all within the dungeon or release one of the most potent evil artifacts on the world if they fail.
