assorted dungeon keys

And if you thought the lock was unusual, check out the keys.  Roll d12.

1. Bronze master key.  Fits 50% of locks on this level or in this part of the dungeon. 
2. Darkwood key with long shank.  Totally non-conductive for electricity.  May be useful for an electrified lock? 
3. Fulgurite key of hexagonal shape that reduces electrical damage by 2 points when used to open an electrified lock. Worth 300gp. 
4. Heavy key of magical red-veined iron that reduces heat or fire damage by 2 points when placed in a lock that radiates heat or flames.  Worth 300gp. 
5. Jet key set into ring carved from a single piece of stone used by ancient wizards.  Warm to the touch, suitable focus for magic jar.  Worth 250gp to arcane collectors, 200gp otherwise.
6. Leaden key that reduces negative energy damage by 1 point if inserted into a lock charged with negative energy. Worth 150gp.
7. Naga-bone key of interlocking small bones for the blade and a bone cameo for the bow.  Worth 200gp for the craftmanship and exotic material. 
8. Plaited red gold and faience key with spiralling blade and bow shaped as a miniature shepherd's crook.   The crook is used to disable a needle trap on certain locks by those in the know.  Worth 300gp to the right people, 150gp to the uninitiated.
9. Rusted iron key with letters SIR etched on bow.  This key radiates moderate transmutation magic.  If placed inside a metal lock, and the word 'SIR' is spoken, lock and key collapse into flakes of rust. This destroys and unlocks the particular lock.  The key is only usable once.  Worth 700gp.
10. Topaz key of rose and orange hue.  Enchanted to be tough as steel.  Worth 600gp due to craftmanship and enchantment. 
11. Vampiric skeleton key, works on locks 50% of time. If touched by bare skin drains 1 point of Constitution then open locks 75% of the time until next sunrise.  Will not be inserted into a lock in sight of a holy symbol.  Constitution loss is recovered by 8 hours sleep
12. X-bladed silver key.  Fits a specific superior lock that imposes a -20% (-4) to picking due to wards.

assorted dungeon locks

Not all locks are created equal.  Some of them are positively odd.

1. Axehead-shaped steel lock of good quality dwarven manufacture. Keyhole where haft would go and intricate wards make it difficult (-10%/-2) to pick.  Worth 150gp to dwarves, 135gp elsewhere. 
2. Crescent moon-shaped superior lock of silver-plated iron. Fiendishly difficult (-10%/-2) to pick due to curved positioning of tumblers.  Worth 250gp to the right people.
3. Dusty copper average lock enchanted to give electrical shock (2d8 damage, save 1/2s) to anyone touching with conductive metal (like most thieves tools) or bare flesh.  Faint, tell-tale hum warns the observant.  Worth 500gp to someone non-conductive.
4. Gorgon-faced average lock weeping red waxy fluid from eyes and keyhole.  This waxy fluid is contact poison, causing a loss of 1d6 Dexterity for 2d6 turns (save for half effect and duration).  The residue loses potency after 1d4 rounds  but the discolouration remains unless washed in wine.  Worth 40gp as the weeping wax is a curse.
5. Knotwork-engraved gold-plated steel lock of good quality and elven manufacture.  Worth 240gp.
6. Mermaid-shaped simple lock of brass and tin, average quality, keyhole where navel is.  Worth 20gp.
7. Ordinary lock of brass and iron, average quality.  Worth 40gp.
8. Quartz lock of good quality.  Immune to rusting effects, difficult (-10%/-2) to pick due to stiff crystalline tumblers.  Worth 630gp. 
9. Sea lock of blue steel will only admit a key when the tide is out, pushing the key out of keyhole at all other times.  Magic can be used to unlock as normal.  Superior quality, worth 1000gp to right people.
10. Umbral lock of lead and iron - only be opened by magic or the shadow of the correct key inserted into the keyhole.  Skeleton keys have a 20% of working if their shadow is inserted into the keyhole.
    Worth 200gp as a novelty.
11. Wolfshead-shaped simple lock of pewter and iron, keyhole hidden underneath plate on which wolfshead is mounted.  Worth 20gp.   
12. Yellow-golden (actually iron pyrite) average lock shaped to resemble a smiling actor's mask.
    Keyhole in right eye.  If left eye keyhole used, a magic mouth activates "Oh dear. You never go left." then commences raucous laughter that provokes a wandering monster check.  Works once only, worth 100gp.

assorted dungeon fires

Roll 1d12 for the burning.

1. Bed of hot embers used for firewalking and post-firewalk barbecue.  Trial by firewalking used by nearby humanoids to determine innocence.  Last meal of condemned takes on whole new meaning.
2. Cooking fire for cauldron of mystery stew. 1 in 6 chance cauldron is occupied by something that would prefer being the eater.  1 in 6 chance of hand or conspicuous body part floating to surface.
3. Divinatory fire used by oracles in diverse ways to predict fate or fortune.  1 in 6 chance an oracle will be available to offer advice on a course of action.  This is totally accurate 70% of the time.
4. Funeral pyre for 1d4 Medium-sized corpses; burning quite lively, difficult to distinguish species due to smoke and charred flesh.  1 in 6 chance some grave goods survive the flames.
5. Furnace used to smelt iron.  A bloomery with chimney stack and animated bellows.  Can create up to 30lbs of iron in a day.  About a week's charcoal and two sledge hammers are stored nearby. 
6. Masonry stove used to heat room and bake.  Uses wood or coal. 1 in 6 chance it is magical.
   Magical stoves can talk and will create 1d6 loaves of rye bread if lit and tended by anyone willing to talk for 6d6 minutes. 
7. Open-hearth forge for creating arms, armour and even  ironwork.  Forge is ready-lit, tended by twin dwarves. Magic is not welcome here without hefty bribes.
8. Punishment for 1d4+2 criminals of heinous crime versus faith and local ruler.  Stakes and pyres are already burning.  1% chance a criminal survives, smell doubles chance of wandering monsters. 
9. Purifying fire being jumped over by 2d4+2 humanoids; taking turns to goad each other into jumping over the fire in order to purge themselves of spiritual taint.  Sinful items are fuelling the flames. 
10. Refining fire kindled to burn off alchemical dross; fumes cause nausea if inhaled (Fortitude DC12, nauseated for 2d6 rounds).  1 in 6 chance of 1d6 gold nuggets (worth 50gp each), still red hot.
11. Sacrificial fire for 1d3 Medium-sized creatures fully aflame.  Offerings are already dead but anointed bodies burn excellently in any event.  Extinguishing will incur divine wrath from nearby clerics.
12. Self-immolating fanatic makes supreme sacrifice to immolate tyrant.  Direct contact does 4d6 fire damage; anyone in 5' risks 1d6 damage.  1 in 6 chance that tyrant's bodyguards notice in time.

mindmap: manageable megadungeon

I blame Greyhawk Grognard of course.  There was a lot of words.  I mean a lot of words.

Then I decided this may be a shade ironic given this was about making megadungeons manageable.

So I thought... mindmap?  Plus I had to give XMind 2013 a spin.

This reminded me just how much good stuff is out in the blogosphere. So for your viewing pleasure...

Mindmap: Manageable Megadungeon (PDF).
Or if you prefer, XMind 2013.

There are numerous lists out there (some included) but keeping track of it all is a challenge.  For those less able to speed-read, this may be some help.  Please provide feedback in the usual location!

assorted dungeon vents

This corridor may serve another purpose.  Roll d12 for unexpected environmental change!

1. Acidic vapours do 1d4 damage per round exposure (save for half), causes exposed metallic surfaces to be pitted unless made of gold, silver, mithril or adamantine. 
2. Air shaft with steady wind, constant turbulence makes it hard to hear.  1 in 12 chance of extinguishing non-magical flames (candles, torches etc.) or plucking loose or flimsy items (e.g. scrolls) from grasp.  
3. Brine pipe used for cooling or solution mining.  Salt water has no intrinsic harmful effects.  May rust exposed metal if left untended for more than a day.
4. Dust-bearing vent.  Fortitude save (DC12) or be blinded for 1d4 rounds.  Anything invisible or hiding is outlined after 1d4 rounds exposure. Scrubbing off takes 2d8 rounds.
5. Exhaust bearing away noxious fumes, cinders and smoke from forges.  Visibility limited to 20'.  1 in 4 chance of being hit by a cinder for 1 point fire damage.  Fortitude save (DC10) to avoid 1 point temporary Con damage every hour.
6. Flaming gas for heating or illumination does 2d4 damage per round exposure (save for half), ignites flammable items.  Flames go out after 1d6 rounds.
7. Gas pipe carrying strange vapours to different parts of the dungeon.  Inhalation may induce effects including blindness, exhaustion, poison, sleep or others (DM's discretion).  
8. Heating vent doubles chance for random encounters due to near body temperature heat.  Infravision is blurred out here (-2 to attempts to notice anything). 
9. Steam vent reduces visibility to 15 feet.  Fortitude save (DC12) per minute or become fatigued due to excessive heat until leaving area.  1 in 4 chance of scalding cloud causing 1d6 damage lasting for 1d4 rounds.
10. Stinkpipe used to vent noxious vapours from underground cesspits or sewers.  Fortitude save (DC12) or become nauseated within the vent and for 1d4 rounds afterwards.
11. Sulphur vent.  Fortitude save (DC12) or be nauseated within the vent and 1d4 rounds afterwards. 1 in 4 chance of burning cloud for 1d4 fire damage for 1 round only. 
12. Water vent sprays water and chill vapour.  Visibility limited to 30'.  1 in 4 chance of blinded by gout of water for 1 round (Reflex save (DC10) avoids).  50% chance of non-magical flames (candles, torches etc.) extinguished.

assorted dungeon utensils

Courtesy of Wikimedia Commons

Some items are just ordinary (or not). Roll d12 for your dressing.

1. Alembic (single vessel with tube for distillation) worth 10gp to an alchemist, potion maker or wizard.
2. Copper candelabra festooned with verdigris and wax.  If properly cleaned up, worth 10gp at the market.  Not really the kind of thing court would want.
3. Ewer of decorated porcelain with handles of dancing nymphs, suitable for boudoir, worth 25gp.
4. Grinder for spices or coffee suitable for halfling-sized hands. Takes 10 rounds to grind a pound of spice or coffee.  Worth 10gp to a coffee-drinker or professional cook.
5. Iron flask engraved with assorted sigils of longevity; looks like a genuine iron flask but holds nothing of any danger or value.
6. Knife of brazened steel with saw-backed blade; usable as small wood saw or knife.  Worth 6gp to any adventurer.
7. Mug with grinning goblin face wearing red cap. Popular with goblinoids as collectible (worth 10gp to them) piece.  Dwarves and gnomes find it intensely annoying and try to get rid of it.
8. Oil scented with rosemary and lavender in crystal vial to aid relaxation and memory   Worth 5gp to an alchemist or wizard.
9. Quill made from giant eagle feather, beautiful to write with, gives a +2 bonus to any writing-based skills where quality of output matters (including forging documents or creating spell scrolls).   Worth 50gp in the right hands.
10. Salt and pepper shakers made of blue and white banded pottery, each as tall as a dwarf and holding 50gp of salt or pepper.  Each worth an extra 50gp to the right giant. 
11. Wooden spoon with foot-long handle carved with dragon motif and protective runes. No game effect beyond preventing burns while cooking.  Intended as a bridal gift.
12. Whetstone useful for sharpening and polishing blades suitable for use by anyone capable.

assorted dungeon ziggurats.

Courtesy of Wikimedia Commons

Sometimes, the architecture is a little extraordinary.

1. Altar to eldritch primordial entity.  Leave an offering (minimum 10gp x dungeon level) at the top and recite the prayer etched in hieroglyphs at the bottom tier for 7 rounds.  Offering disappears in cascade of silvery flaming orbs. 10% chance per dungeon level of getting +1 bonus on next dice roll.   
2. Black ziggurat offers interdimensional transit to other black ziggurats. 10% chance per dungeon level the ziggurat is activated when ascended and transports you somewhere very different indeed.
3. Elevator upon top tier that transports to megadungeon location with a 10% per dungeon level chance of working.  Elevator ascends or descends depending on relative altitude to ziggurat.  Jumping off early has a 50% chance of stranding you in the Nine Hells (DM's choice).  
4. Generative ziggurat augments summoned creatures.  Activate by reciting chants on each tier as you ascend.  Casting a summon spell from the top tier grants creatures summoned +4 to Strength and Constitution for the spell duration.  This must be repeated for each summon spell cast.
5. Inductor of mystical energies.  Any one charged magical item (casting a maximum of 3rd-level spells) left on the top tier of the ziggurat gains a charge per uninterrupted day left there.  Once fully charged, the top tier glows with bronze faerie fire.
6. Kennel for hounds of retribution.  Recite the prayer on each tier then drop a scent-laden item down the grate on the top tier to unleash 1d6+1 hellhounds from lower tiers after the scented individual.
7. Meditative center. By reciting the chants carved into the steps and meditating atop the ziggurat for 30 minutes, consciousness is expanded so a meditator can commune with infernal entities.
8. Offertory to gods topped with blood-stained chains used to hold man-sized sacrifices. Hieroglyphs on steps bid a pleasant meal in the language of devils. 
9. Rostrum that amplifies spoken words of those at the top by a factor of two.  A whisper can be heard as normal speech and speaking is equivalent to shouting.  Actually shouting causes pain (-2 to hit and any Dexterity bonus) to anyone within 30' of the ziggurat.  Sonic attacks upon those at the top cause +50% damage and impose a -1 penalty to saving throws.
10. Tomb of abhuman dignitary.  Hieroglyphs on steps detail mighty deeds, foes slain, royalty ravished and gods defied. 10% chance per level that tomb hasn't been looted; 1 in 6 chance of hideous curse befalling tomb robbers.
11. Vestal flame atop hollow oil-filled ziggurat to purify sacrifices provides helpful illumination.  Refilling this is done through a hidden port in the third tier.  Oil refuelled every sunrise by three acolytes with ewers of consecrated lamp oil. 
12. Ziggurat for ziggurat's sake.  Pay no attention to the priest behind the curtain.

assorted dungeon bridges

Roll d12 for your conveyance across.  Mind the gap.

1. Bone bridge formed from spine and ribcage of immense reptile lashed together with magically-preserved sinews.  Worthy example of caveman or barbarian engineering. 
2. Chitin bridge formed of interlocking lacquered giant insect exoskeletons capable of bearing immense weight with barely-perceptible creaking.
3. 'Dancing flagstones' rise between massive levitating menhirs to form a 5' section of bridge per person, moving ahead or behind according to their direction of movement. Loss of consciousness results in the relevant section collapsing after 1d6 rounds to drop hapless delvers. 
4. Glowing blue coals held together by shimmering sheets of force form underlit span.  Edges are very hot, touching them does 1d4 fire damage and ignites flammable materials. Obvious magic is obvious,  worthy example of efreet engineering.
5. 'Invisible' buttressed bridge of thick glass blocks.  Slippery underfoot, edges can be found by spilling sand, dust or opaque liquids.  Those aware of stonecraft or secret doors know where the edges are.
6. Lethal wood and rope bridge with missing boards.  Jumping up and down or combat gives cumulative 10% chance per person that a board will break underfoot with 1 in 6 chance of falling through. 
7. Net of chains forms unsupported bridge.  Walk slowly or crawl swiftly to avoid stumbling. Lose Dexterity bonus to your AC and if you drop something small here, it's 80% likely to be fall through.  
8. Paired ropes allowing man or elf-sized to go hand over hand while walking the lower rope.  Dwarves have to reach up while halflings cling sloth-like or try tightrope walking.  Combat might be risky, kiss goodbye to any Dexterity bonus and try not falling if you get hit.
9. Petrified bodies cemented together so you walk upon stone backs to cross the bridge.  Realistic faces and hands as decorative features. Casting stone to flesh makes the bridge collapse after three rounds in a Grand Guignol.
10. Reinforced stone bridge with tree designs.  Everburning braziers and nightingale flagstones makes moving stealthily across it extremely difficult (half normal chances to do so).
11. Span of woven giant spider silk affixed by magical adhesive,  Springy underfoot yet surprisingly strong. Combat not advised, sharp weapons or fire will destroy the span if 20 points of damage is done to a 5' section. 
12. Zombified colossal worm suspended on dozens of hooked chains, surgically mutilated to form a covered bridge.  More hit points than a small European country, smells vile, guarded by ghouls who snack on it without destroying it.  Cannot be turned by your cleric, though the ghouls can be.

assorted dungeon horns

Horns are usually trouble.  At best adorning simple animal or capricious fey.  More often, the weapon of monster, mutant or infernal being.  Yet that won't stop them being converted into musical instruments or other useful items.  Roll d12 to get the horn.

1. Alphorn of pinewood carved with zig-zagging mountain patterns and star symbols.
2. Carnyx made of black curling horn with bell carved into demonic head.  Makes a frightening bellow if played.
3. Ear trumpet of curved goats-horn which if held to the ear improves the ability to discern sounds.
4. Gunpowder horn with brass cap and lid; holds 1d6+4 doses of powder for primitive firearms.  The horn keeps the powder safe from fire, water etc.
5. Ivory drinking horn with etching of warrior spearing a boar and braided red and indigo velvet carrying strap with fancy tassels.
6. Kudu horn used for sacred rituals; spiralling, dun-coloured and painted with flecks of gold leaf.
7. Mead horn made of gargoyle horn.  Slate-grey and triangular.  Can drop from most any height and not break.
8. Ox horn knife handle.  Striated lines on pale horn, fits a human, elf or dwarf hand well.  Carved to fit a short-bladed knife.
9. Rack of twelve-tined antlers on gold-inlaid bassinet.  Worth at least 100gp to the right people.
10. Twisted reddish dragon horn with brass mouthpiece.  Tall as a halfling, used as a signalling horn.
11. Unicorn-horn dagger with short hilt wrapped in pale leather.  Strikes as a +3 weapon.  Unicorns, elves and all sylvan folk are hostile to the wielder.
12. White rhino horn mounted on ebony handle as a ritual dagger.  Bound in red and black leather thongs matted black with blood.
    

assorted dungeon talismans

Bling courtesy of
Wikimedia Commons

Roll 1d8 for your minor magical jewellry.

1. Blessed talisman gives +3 bonus to reaction rolls with good creatures. Evil creatures refuse it taking -1 to hit and AC if forced to wear it.
2. Friendship talisman gives wearer a +1 bonus to reaction rolls.
   If it changes owner, a new owner must polish it to gain the reaction bonus.
3. Healing talisman adds 1 hit point for every 8 hours rest. If it changes owner, a new owner must put a drop of their blood on it.
4. Invisibility talisman gives +10% to hide in shadows checks. If it changes owner, it must be washed in wine to activate it's power.
5. Luck talisman allows a re-roll for one attack roll or saving throw once a day. The re-roll is binding and only one re-roll is allowed.
6. Magic talisman gives wearer a +1 bonus to saving throws vs. spells and this increases to +2 on nights where there is a full moon.
7. Protective talisman gives +2 bonus to AC vs. missile attacks. If it changes owner, it must be washed in holy water to activate it's power.
8. Vile talisman gives +3 bonus to reaction rolls with evil creatures. Good creatures refuse it, taking -1 to hit and AC if forced to wear it.

assorted oils and ointments

 Table XV: A dozen oils and ointments.

1. Almond balm in blue enamel tin
   When smeared on face and hands, gives +2 on saves against cold damage or penalties.
2. Bitter chrism in tiny crystal vials.
   When applied to brow, gives a +2 to saving throws vs. charm or possession.
3. Dark oil in clay bottle for taming unruly hair. 
   If applied to the hair, reduce any Charisma reaction penalty by 1 due to grooming.
4. Herbal paste in black pot 
   Enough blade venom to poison a single-handed blade, spearhead or five arrows or crossbow heads.  For next 1d4 hits, save or take 1d4 extra damage.
5. Liniment in small copper bottle.
   Heals 1d4 Strength damage when rubbed into muscles (takes 1 turn).
6. Oil with pickled spices within.
   Makes any food cooked with it most excellent.  Worth 2d6 gp to connoiseurs.
7. Ointment in red wood jars.
   Helps soothe pain.  Each jar heals one hit point in a 24 hour period.
8. Pungent paste in sealed clay jars.
   Negates ability to track by scent for 1d6 hours due to persistent odour of rotting violets.
9. Sweet salve in yellow wax jar. 
   Made from royal jelly, applied all over a naked body it reduces physical age by 1 year.
10. Unguent in white clay bottle.
    Adds +1 to Charisma for 1d8 hours when rubbed into face and hands.
11. Urn of exotic oily scent.
    Negates bad smells and gives +1 on reaction rolls with humans and humanoids.
12. Witches ointment in a black clay jar. 
    Whoever anoints their naked body can fly (as spell) for 1 turn.

assorted dungeon ceilings

Roll 1d12 if you're redecorating.

1. Billowing suspended drapes lends an opulent air.  The drapes are neatly repaired canvas in strong colours and treated to resist flames.
2. Dome with shaft of light coming down from cupola (circular hole in the top of the dome).  The cupola might rarely drip with water.
3. Dripping ceiling with water drops splashing 1d6 party members each round with icy-cold, dirty water and staining their cloaks or shoulders.
4. Fresco resplendent with fine artistic interpretations of maidens, heroes and the gods.  Artwork is uplifting and inspires wonder in it's viewers.
5. Glowing cracks in the ceiling emit heat and light equal to a coal fire though light provided is greenish-white and flickering.
6. Hooks set in the ceiling at regular intervals (d6+4 feet apart) for the suspension of objects or chains; the room may have multiple purposes.
7. Illusion of night sky with strange stars and 1d4 moons.   Some constellations are familiar but seen from a different perspective.
8. Kaleidoscopic mosaic that shifts in slow geometric patterns.  Distracts the weak-willed and gullible (add Wis penalty to initiative).
9. Netting hangs in long hammocks capable of supporting bundles of items large enough to stay caught in the mesh of the net.
10. Painted ceiling showing maps of neighbouring nations with location of dungeon at the map's centre.
11. Racks suspended from ceiling holds selection of equipment in readiness for use.  Arms and armour may be typical, climbing gear is less so...
12. Strange sculpture of metal and glass casts shadows of leafy boughs on the upper walls when lit by torchlight.

assorted dungeon statuary

There is always a need for strange statues in a dungeon.  Don't blink.

1. Alabaster elfmaid with mouth open in song fills 30' radius with unearthly music, calms 2d4 hit dice of listeners to inaction.
2. Bronze bull with sharp horns gives +1 to AC for 9 – level hours if an offering is made to it.
3. Copper wizard with staff lights unlit torches within 10' every 2 hours by harmless electrical discharge.
4. Crystalline woman in court dress when not looked at to reflect the mood of those within 30 feet.
5. Gem-eyed demon bearing a brazier illuminating up to 90' radius in torchlight.  Gems are 100gp each. 
6. Golden child offering blessing gives +1 to all saving throws for 9 – level hours if offering is made to it.
7. Iron warrior woman with battleaxe gives +1 to hit for 9 – level hours if an offering is made to it.
8. Leaden, shapeless many-eyed thing causes nausea in observers, irresistable to oozes or slimes.
9. Many-tentacled horror causes dread in observers.  If given to an undead they leave with it. 
10. Marble angel with elephant head gives +10' movement for 9 – level hours if an offering is made to it. 
11. Silver youth with snakes in hands cures 1 hit point every 2 hours resting within sight of the idol.
12. Verdigris man with octopus head gives +1 to damage rolls for 9 – level hours if offering is made to it.

eggs is eggs, innit?

Czech decorated eggs courtesy of WikiMedia

Table V: A dozen dungeon eggs

1. Alabaster egg plays magic tinking chimes for 1d6 rounds when sat on it's end and spun clockwise.
2. Cock's egg laid by an enchanted rooster, this tainted item spawns a basilisk if incubated by a snake.
3. Duck's eggshell grenade filled with powder.  A successful to hit roll on a foe with eyes blinds them for d4 rounds.
4. Goose eggshell holds magic dust that reveals invisible objects, turning them pearlescent for 9 rounds.
5. Jewelled lacquered egg crusted in semi-precious stones worth 1d6 x 100gp.
6. Painted ceramic egg with formula for a 1st-level wizard spell in tiny writing.
7. Pitted egg of smelted iron, weighs 3 lb, workable into iron or steel or a meal for a rust monster.
8. Puzzle egg of brass and iron (needs Open Locks roll to open) contains a gem worth 100gp.
9. Quail's eggshell filled with a dose of dust causing inhaler to breathe water as air for 9 – level rounds.
10. Rubbery black egg useful as diversion.  If thrown, it does 1 + Strength non-lethal damage.
11. Tarnished silver egg contains 8 ounces of high-quality snuff (8gp) kept in perfect condition.
12. White, smooth egg, left to it's own devices a baby amphisbaena will hatch in 1d6 hours.

megadungeon mercantile

"Entrance" by Ian Mcraig

This discussion of merchants in the dungeon opens up interesting ideas.  While having hobgoblins treat their weapons like heirlooms is nice flavour, supply of commodities like polearms, food and basics like clothing take on new significance.  Set routes like a "Spider-silk road" used by drow traders linking up megadungeon sections make useful design elements.  Routes establish relationships, suggest potential treasure and add flavour.  Trade routes have made and destroyed kingdoms.  Even in the smaller scale,  smuggler runs and trade discoveries make interesting adventures.  Profit is always popular with NPC adventuring types...

Underdark commodities - Metals and minerals are obvious choices, including gold, iron, salts, stone, gemstones, oil and coal.  Animal and insect-based products are plentiful.  Fabrics include assorted leathers (e.g. chitin, giant snakeskin), woven material (e.g. cloth of gold, cloth of silver, mohair and spider-silk), furs (e.g. cave bear, displacer beast) and exotic hides.  Parchment and vellum make scrolls and books with ink (e.g. cochineal, sepia) bound with metal plates or inlaid bone marquetry.  Ivory (antler, horn) and related trades (scrimshaw) replace wood-craft (scabbards, hilts and smaller hafts) bearing equal decoration.  Longer hafts are forged of metal, making such weapons more resilient, heavier and expensive.  Arms and armour from the Underdark have history, from exquisite dwarven platemail to jagged orc battleaxe. Incense is made of amber, operculum and exotic reptilian musks, fluorescent and phosphorescent dyes are sold while psychoactive mushrooms and mould provides recreational drug sales.

Surface delicacies - Goods from the surface that cannot be found below are valued.  Foodstuffs, wood, wine and other sundries gain unexpected value. Spices, incense and salt all created trade routes and do so in dungeons.  Honey and sugar in particular are popular choices.  Wood may be treated with resins or pickled in vinegar to increase strength and kill mold.  Weapons and armour are standard quality and plain but odd bits of craft slip down to the dungeon - arrows and crossbow bolts are particularly popular given the scarcity of wood and lack of adequate bone or ivory (shafts have to be footed or they're more likely to break).  Charcoal is popular with traders - light, burns hot, useful for alchemy and rare since most wood is used for doors or structural support.  Inexpensive, durable woven fabrics are at a premium.  Plant-based incenses and resins are popular and command a pretty penny, narcotics are a potent trade item as is simple pipeweed.

Logistics - Walking between the surface world and underworld needs a specific attitude and attributes. A willingness to deal with inhumanity makes the typical peddler world-weary, well-armed and familiar with magic.  The use of wagons is limited to large passages and caves.  Most routes however fit the description of 'twisty set of passages, all alike'.  This means hand carts, bearers and the dungeon mule (or local equivalent).  Climbing between levels, fording underground rivers and finding safe trading points make a dungeon peddler's lot interesting.  Many underdark races are unpleasant, conducting trade negotiations in mutual strength with an eye for treachery.  Negotiations with 'friendly' duergar may involve mutual paranoia, threats of enslavement and drinking sessions with mildly toxic spirits.

Merchants who trade in megadungeons may not command wagon trains or armies of fat bodyguards.  Rather they move between worlds, wielding fantastical wealth and a handful of elites.  Find the right customers and you have a sweet life indeed.  Dealing with some communities has risks -  trading with aboleth is a fast route to indenture as a servitor.  Yet the cautiously bold will take up trading within the megadungeon, forming a hub for communities to gather together.  From these seeds, dungeon ports and sunken cities provide fertile breeding ground for these entrepreneurs.

underneath the arches

Arches are an under-used feature in dungeons given their history.  To rectify this shocking state of affairs, here's a table of them since the d12 needs more tables devoted to it's use.

Table 1: A Dozen Arches.

1. Bald arch – Stones show signs of decay.  1 in 6 chance stone falls out for 1d6 damage and 10% chance the arch then collapses, blocking access until the rubble is cleared.
2. Blind arch - Sealed to stop passage between areas or for decoration.
3. Carved arch with dozens of faces. Each face has sunken pits for eyes.  10% chance per dungeon level an obscuring mist reducing visibility to 3' surrounds the arch.
4. Conspiring arch is magically linked to another arch so words spoken at one are heard at the other.
5. Decorated with skulls cemented into the arch.  10% per dungeon level chance d6+4 skulls speak to whoever passes through.
6. Gilded arch with 10% per dungeon level chance of d6x10gp of gold leaf that can be removed (if not it's gold paint or iron pyrite).
7. Memorial arch contains the tomb of a fallen dignitary.  10% chance per dungeon level the tomb still has it's original occupant and grave goods.
8. Natural arch made of a single piece of weathered rock.  10% chance per dungeon level of swirling mists in the arch that act as a crystal ball.
9. Raised portcullis has 1 in 6 chance of falling on unwary.  Winch to raise bars on other side with 50% chance use will draw monstrous attention.
10. Teleportal arch that instantly and safely teleports those passing through  to an identical linked arch elsewhere in the dungeon.
11. Triumphal arch with carvings and commemorative inscription to mark historic event (GM's choice). 
12. Vault – An arched ceiling runs the length of the room.  Drow optional.