It aint really a mega dungeon maybe just a huge single level complex. I have noted new school DnD seems to have less encounters. Since i started running this game I have not looked up a single monster. But sadly I can still locate 80s dragon articles on anything (ditto for x-men, new mutants or moonknight comics).Im looking for this to last 4-6 levels and possibly a diversion to the city. Found thieves world tables. Sigh PDF is easy in i tiny apartment.
Hidden behind a waterfall, the complex was on a castle on a hill covering the only pass through the mountains. Since then the castle has been destroyed and a river run over it depositing a hundred yards of soil on top and wearing away the land beyond the castle into a low laying swampy forest. The castle didn't really last long or leave much evidence. Some say it was a forgotten outpost of the early empire over 4000 years ago but actually it is one of thousands of nameless lost kingdoms less than a days ride across.
The castle was in fact built on top of an entrance to the underworld 6000 years ago. It was the site evil dwarves had built a formal temple and administrative complex for their expansion. They worshiped Erishkigal, in her aspect as Dungeon keeper and mother of monsters. Good human barbarians, elves and dwarves destroyed the cult and built the castle. Humans stayed on and enjoyed the gifts of metal and civilization the demi-humans showed them. After a thousand years of benevolent human occupation someone found the dungeon Lv of the castles entrance the the dark waters of the underworld. Undead evil Dwarves and demons broke out and destroyed the kingdom and the castle. Demihumans re-directed the river and destroyed the forces of evil and retreated to their secret strongholds.
About 300 years ago the shanty town of prospectors was born. Prospecting for isolated clumps of metal to be found was profitable. Bit then the tombs of a previous dwarf kingdom began to be found. A fortified Village was built with empire funds. The empire built 100 yards of road then lost all record of the outpost. They even have their bonfire tower to signal for help ready at all times. The current rulers hope the empire will contact them still and consider themselves loyal vassals (who haven't paid tax). The new common scum of fighters and thieves who go prospecting think the locals idiots. But most of them die in the wilds from goblins or undead dwarves.
Life in the Dungeon has been more active of late. Multiple factions occupy sections of the maze.
Undead (Common) - areas are silent, lifeless and dark, with smell of death. Control the underworld entrance, Most are common mindless undead, but a dwarf vampire lord and his succubi lover control the ferry to to the underworld entrance. They serve Ereshkigal and do some surface world business on her behalf. There will be a few wraiths, mummies and wights too. Should be the last part to explore - most constantly renewed by the underworld ferryman. Human undead are more recent weaker types of undead, some of the Dwarf undead are thousands of years old. Minor Undead 40-60, Major Undead 10-26. The Undead may leave you alone if you hold a symbol of Ereshkigal and think piously, which the bugbears and cultists use to get around. A few evil dwarves use this and get missions from the Vampire and cause trouble in Dwarf town.
Dwarf town (Uncommon) - area smell of smoke, forge and booze, well lit by lanterns. Modern dwarfs have controlled 8 room in the center. They have placed protection from undead wards. Most are Black and Red dwarves but a Silver runs the tavern-forge which runs the town. He made the wards and is LN. Other dwarves vary in alignment and may join the party. They will sell some grenades, cold iron quality weapons, and perhaps a door-charge to the party. 15-30 Dwarfs are here any time. They are exploring the region to see if ancient evils are returning. Several wield guns. Humans who buy shares may enter and stay and eat all the canned dwarf slurry and grog they can handle. They may even cross train with dwarves if the company like them.
Cannibal Chaos Cult (Common) - lit torches, cult graffiti, rubbish, chewed bones and dung. This cult of man eaters comprises of several character classes. They were formed by a mad priest of Erishkigal as the Devouring Maw that eats all. They were driven from the city and appeared locally to start eating the prospectors and ancient dwarf remains. Until the town hunted and drove them here. This is their promised land and they feel close to the goddess. The even eat undead. Purify food and other spells prevent them all dying but they are very mad. They fight and stalk as mad killers not rational warriors. There are 30-45 in the dungeon and some prisoners and converts undergoing brain washing. 20% have 1d4 Lv of some class. All are Chaotic.
Wham Bam Bugbear Clan (Common) - pictogram and drawings, bugbear musk, candles lit. With a few goblin slaves, hobgoblin flunkies and a few pet Yeth hounds this Bugbear clan were called by Erishkigal and have been living off goblin communities and prospectors since. Their Witch Doctor has warded Their zone from undead but is willing to create his own. They also feed off the Slime Gods lair. They already hate the adventurers for bothering goblins. They harbor the survivors who could not fit on an escape bat. Chief Grumchala will enjoy sacrificing eating and mating with the party but he could be bribed. 16 Bugbears, 24 Hobgoblins and 8 goblins. Goblins mostly young and old but willing scouts but will surrender or flee.
Super Kobolds Adventure Team (Rare) - leave scattered kobold tags around dungeon. These dont live here but are semi divine heroes of the tin mine clan. They are all 4HD and have other magical powers. The 7 are all brothers, spawned by the Kobold God choosing the prettiest kobold born in generations as their mom. They spend their time trapping the dungeon and hiding in air vents and drains. Each has a blue cap and a cute little red salamander skin cape which halves fire damage. They also like attacking weakened and retreating parties. They may even use Kobold poison, burning metal floors and radioactives which dont harm them. They hope to get some magic then spawn a kobold master race to cleanse the world of big folk. Any who kill one is branded by the kobold gods so all kobolds can sense them within a mile. If they are all killed the slayers whole band recieve an extra random minor curse.
Hungry Gnolls Adventurers - (Uncommon) leave demonic rune tags and urine and feces marks. These gnolls seek horrible things to eat and treasure or pay homage to the underworld goddess and their demon father. Some also bring a pet 8HD Hyenadon (but he has trouble turning tight spaces) or 1d4 some 4HD 2d4 bite Hyena . The team will re stock losses and return, they will never fight to the death. They may track the party and stalk the home. Typically parties of 8 with a few pets. Plenty of Gnolls out there to spare.
Curious Lizard Men (Uncommon) - little impact and no signs of passage, hide in slime gardens. Guided by their Serpent Man Wizard 6th Lv, Snurgrump the chieftain and his pet Cave lizard are gathering exotic food species in the Slime gods grotto. They dont really want to fight but characters may well attack them on sight. The Serpent man Smergroth may suggest attacking the party for spells or items. He is also seeking remnants of pre-dwarvern serpent man ruins. Usually party of 8 plus Snurgrup and a Smergroth. They could be reasoned with but dont realize humans are sentient. Draconic might be a good language to impress them.The leaders can replenish their troop daily as long as they escape.
Mystery Wizards (Common) - Some may leave strange signs or booby trap spells. For some reason various forgotten elder races of humanoid spell casters have been awakening and coming to these ruins. Their motives are unfathomable but they are a threat to any adventurers. 1d4+1 some may have charmed or summoned minions too.
Rival Adventurers (Common) - personal or party names and "was here" graffiti and etching. Plenty of small bands of rogues and warriors come here looking for loot. Most fear the undead and think adventurers are monsters or rivals. A few have a priest or wizard but most have no magic (1-45% Warrior, 46-90% Rogue, 91-95% Wizard or Sorcerer, 96-100 other class. Some may wish to join if they are weak. Some might ambush the party on the way out. After a few raids from the party a new band from the city may arrive, even led by ex-henchmen. 1d6+2 in a group of 1d4 Lv each.
Slime Gods Grotto (Common) - fungal blooms coat everything, dripping wet. Rugose columns of slimy fungus and fetid ooze, dripping with humidity. Howling fungus is everywhere hooting and squealing when players come near. The river leak here making the level a dank stinking mildew trap. A Druid of the underworld fungi order spread an ecology of fungi and slimes, attracting giant bugs and lizards and frogs. Some of these creatures wander about the dungeon hunting for food. Some dungeon denizens speak of a slime lord of fungus but actually it is a remnant of the Lv10 Druid, now a ogre sized shambling horror. He uses spells to enlarge critters and spawn monsters every day. He is invisible when motionless and blending into fungi walls. He will aid lizard men and leaves them healing berries (mushrooms in his case). His cult praise Jubilex but see him as an elemental being of nature and neutrality rather than demonic. New monsters can be spawned from here daily. A Druid might get a chance to talk.
The Underworld ferry dock. For a coin per person and reading the multilingual monolith aloud a ferryman will take them to the underworld. Not really sensible to get there yet. Party left a magic mirror somewhere earlier. Most searchers never find the secret door. Its guardian Dwarf Vampire and Succubus are a big challenge and will have some nice loot. The succubi may be sent to entrap the party when they are seen as a threat to the dungeon order. Whatever the outcome - this site will continue to attract evil.