So here is a suggestion: Lets build this adventure based on the map available there.
STONE MOUNTAIN
THE PIT: A thousand years ago all manor of fiend poured from the Pit to ravage the surrounding lands in a torrent of Entropy. Civilized peoples eventually sent a Powerful Wizard who pushed back the tide and entering the caves of this pit of Entropy found the cause. A Goddess had been shackled to an altar and violated with dark magic that opened a Gate of Entropy in her womb.
Now she birthed Shadows straight from the deepest madness of Entropy. The Arch-magi Yan Madol retreated for a time to find a solution while his apprentices perished one after the next to hold the line.
Since then the Annis Enyasha the Terrible discovered that the only way to enter the Pit through the Barriers created by the Seals in place was riding a Nightmare. She was eventually able to penetrate the Wards and gain access to the Sacrificial Chamber.
THE GREAT STONE SKULL: The Great Stone Skull was carved by the surviving Apprentices of Yan Madol to widen natural caves and build a fortified approach that could be collapsed to protect the Seals from penetration.
The Entrance
The great dark skull that is stone mountain stares back at you during your approach. The entrance to the caverns beneath Stone Mountain is a dark cave through the mouth. The eyes of the colossal skull seem to shift disturbingly as you approach the cave entrance.
Anyone attacking the eyes with a missile weapon forces a scout to retreat from his observation post. If they cast sleep, the Kobolds will not be alerted to their penetration of the Caves.
In The Mouth
The cave entrance is lined with a stone ridge that are obviously meant to be teeth both below and above forcing you to slip through the space by bowing your head as you straddle the lower teeth. The Cave is rough and dark and there is a Cut Stone tunnel in the back wall leading you in further.
{Three Crab Spiders drop from webs behind the upper teeth on those few stepping through the narrow space between the teeth}.
Beyond the Mouth of the Mountain which is little more than a large cave, a Cut tunnel leads you into a great hall with two rows of Wooden Columns supporting Timber Beams running the length of it. The Stone of the Ceiling seems to be supported by the Timber. A terrible creaking noise comes from the Timber and Ceiling and Dust continuously falls from the ceiling.
As the PCs enter the Hall, Oil is poured on them from a Hole directly above and set on fire (this happens only if they fail to take out the sentry standing in the Eye above the entrance). The Ceiling is at 100% chance of collapse and will do so if the Timber Columns are Damaged in excess of 10% of their HP - the oil fire will do that. The Noise of the Creaking timber and stone masks the presence of three dire rats.
Stairs are cut in the stone walls from the hall allowing access up to the next level as well as down to a lower one.
Dimensions: 60’ long x 60’ wide x 20’ high
Beyond the twenty casks marked Flamable Oil, you see two huge holes through which can be seen the open sky. Each Eye has its own Scout watching for intruders. Camped here behind the eyes are a group of seven Kobolds armed with unusually nice weapons (Shortswords and Blood Red Studded Leather Armor fitted for each individual).
If the Scouts see intruders they prepare to dump Oil from the Casks down a Hole into the Hall of wooden Columns. They will be alert to anyone coming up the stairs unless the Scouts were put to sleep at their posts.
The Brains behind This
Like the Hall directly below it, the ceiling of this great hall is supported by heavy wooden Columns holding up timber beams on which the roof of the cave rests. This one is however somewhat different. The Columns are all carved into Men. At the end of the Hall, a shifting dark figure sits on a throne.
The Wizard sitting on the Throne is an illusion. If he disappears (the PCs dispel the illusion) the wooden Golems will release the roof timbers and the mountain will collapse. The wizard can only be dispelled if they get to the lowest level of the Dungeon (The domed city) and disable his Magic. Hall The carved wooden throne is worth 500gp (weight: 500lb).
Dimensions: 40’ long x 60’ wide x 20’ high
Down a long winding stairs is the 60’ wide Lower Hall. The stone ceiling in this particularly long hall is held up by terrible wooden Humanoids propping timber beams. At each end of this timber columned hall is a very large bronze gong. At the midway point in the floor of the hall is a large twenty foot diameter bronze Seal depicting terrible fiends.
These Wooden Columns are also Golems. However, they will only stop holding up the timber beams propping the ceiling under one condition: The PCs seeking to Open the Seal must strike both gongs simultaneously. If they do it correctly the Seal will open to the lower levels. If they get it wrong, The Golems will release their hold and the Mountain will collapse after three rounds. If removed the Gongs are worth 1000gp each (weight: 10,000lb). This first seal is more a door to the lower levels. Opening it does however draw the attention of and Ethereal Marauder.
Dimensions: 120’ long x 60’ wide x 20’ high
The Crypt of a Thousand Martyrs
Beneath the Seal a long sloping shaft ten feet in diameter leads you down into a long narrow crypt with a thousand bodies lying in niches in the Walls. These are the remains of the Thousand Apprentices of Yan Madol who gave their lives to hold back the tide of entropy. With each are their spell books.
For those prepared to risk the wrath of disturbing the long dead, The Spell books offer a considerable selection of Magic. Amongst these thousand Apprentice Wizards are every 0-level, 1st level, 2nd level, 3rd level, and 4th level wizard spell in the PHB and a few magic items appropriate to Wizards between 1st and 8th level. Books with paper pages having not been invented during their time - these are sealed boxes of scrolls of beaten Gold foil in brass tubes with brass stoppers at each end. Amongst the thousand Martyrs are 4 Large Ogre Skeletons which attack from each end of the narrow hall.
Dimensions: 20’ wide x 200’ long x 20’ high
The Second Seal
This room is illuminated by three glowing globes of light that float above the Seal. It is almost identical to the one that kept you out of the crypt of a thousand corpses.
Three beautiful voices speaking in overlapping song begin to inform you that this seal was laid in place by the Arch Mage Yan Madol while his thousand Apprentice wizards held back the tide of Entropy pouring from the Pit at the cost of their lives. Apparently on Completing this seal he ventured beyond it and locked it from the inside.
The Three glowing globes are Lantern Archon and will attack if the PCs attack the Seal. Anything with an evil alignment is unable to approach within ten feet of this Seal. It can be opened by the three Lantern Archon – they were deceptive when they said it was locked from the inside. Normally they will not let the PCs pass but if the PCs explain that a Hag riding a nightmare has access to the pit and this is the only way in they will let them pass and lock it again when they are through.
A Stable for a Dark Ride
As you venture down the Stairs from the Second Seal you find that this substantial cave has but one occupant: A Nightmare of huge proportions thunders toward you from the far side, a hungry look in its burning eyes.
This Huge Nightmare is Ilmayan, Steed to Enyasha the Terrible (the Annis currently repairing the Altar of Bone in the adjacent sacrificial chamber at the bottom of the Pit). The Nightmare was grazing on a few dead Halflings hanging from meat hooks at the far side of the cave but noticed the arrival of fresh food. The Dead Halflings are the ones who were abducted by a Hag on a demon Steed a few days ago.
The Sacrificial Chamber
This large cave is directly beneath the Pit. There in the centre, illuminated by the light of several tallow fires around the edge of the cave is a little old woman sitting on an obsidian block. She appears oblivious to your entry as she continues polishing a skull on a Staff made from a Human Spine. Around her numerous hundreds of Skulls all appear to have been polished and prepared with carvings of frighteningly intricate designs.
Enyasha the Terrible (the Annis who rides the huge Nightmare – stabled elsewhere) is currently putting the finishing touches to her Altar of Sacrifice. She is quite aware of the PCs entry into the Cave and intends sacrificing all of them on the Obsidian Altar. She has a selection of Bone darts enchanted as single use magic missiles capable of auto-hit. She will use her darts of bone against any wizards or clerics mumbling a spell.
The Lake of Shadows
As you lower yourselves from the hole in the ceiling of this vast cavern toward the shore below you, the vast Cavern a half mile across and a quarter mile deep stretching out beneath, you can see there is a Domed Citadel on a distant island at the centre of a lake of dark water.
This vast cavern is near half a mile long and a quarter of a mile in depth. The lake water is in fact a “fluid” made entirely of Shadow.
At residence in the Citadel is the Imprisoned Goddess. Her only companion is the long deceased Wizard Yan Madol. The Goddess is not particularly tolerant of intruders and will attack anyone disturbing the corpse of Yan Madol.
Enchantments kept “things” from leaving via the Pit. Once the Seal worn by the Goddess is destroyed, The Shadow “liquid” will return to its true form becoming a hundred shadows. If they destroy the seal their home town will be destroyed by an army of a hundred Shadows while they are “caving” as Shadows armed with Scimitars of Entropy descend on their community.
Which rule set is to be used for the adventure btw?
Right Now it is just a raw idea. So any Rules from OD&D to 4th Edition could be used but if we develop this basic description further Perhaps 4th Edition.
KEY TO LEVELS
Upper Level: Behind the Eyes & The Brains behind this
Level 1: The Entrance, In the Mouth & The Hall of Wooden Columns
Level 2: The Low Hall
Level 3: The Crypt of a Thousand Martyrs
Level 4A: The Second Seal
Level 4B: An Inconvenient Treasure
Level 5: A Stable for a Dark Ride
Level 6: The Sacrificial Chamber
Level 7: The Lake of Shadows
Is the party starting at 1st level for this?
PC STARTING LEVELS: Lets say 10 total PC levels should put them in a Hard fight with a Hag and her Nightmare. The Kobolds are about equal because they have control of the burning Oil and the ability to drop a mountain on the PCs. The PCs only have the problem with the 100 Shadows armed with enthropic scimitars if they pooch things badly.
As for the Imprisoned Goddess, If they are not polite, they will probably die horribly.
STONE MOUNTAIN: A Multi-Adventure Setting.
PC LEVELS.............................ADVENTURE DESCRIPTION
7..........................................Hunting Party (Hunt down Kobold Raiders hold up in the Stone Skull Keep)
21.........................................A Hag and her Horse (Hunt Down the Hag Riding the Nightmare who abducted some Halfling Villagers).
?...........................................The Third Seal (Free a Goddess from an eternity of Imprisonment without getting the Village killed by an army of Shadows)
This is the missing chamber (4b).
This is little more than a long cave perhaps twenty feet wide and fifty feet long. Perhaps what gets your attention is the large vein of gold in the rockface.
There is 30,000cn of Gold Ore in this gold vein (12,000gp processed). Unfortunately the cave is at 19% chance of Subsidence and mining the Gold will bring this up to a whopping 24% (requiring a cave-in check). Mining will draw the attention of any remaining Undead from the Crypt as well as a few of the Guardians from the second seal.
The menacing Pit of Shadows still opens into the dark world so far below the surface. These days it is the nesting site of a million Stirge, the deafening cries of their Stirgesong sinks terror into your heart.
DM: This event occurs as a fourth Adventure at any time post destruction of the Hag and the Freeing of the Goddess in the Domed city. The Pit becomes a nesting site for stirge and the population achieves a million of the creatures so that they have become a problem.