For Christmas this year, Sean McCoy has given me a community project to be excited about: dungeon23. There are a lot of people compiling resources for this project and all of its variations, so I won't attempt to cover that here.
An altar is a table intended for sacrifice. Altars are shaped in the semblance of the god to which they are dedicated. It is a conduit to a higher power, and prayers to the appropriate divinity carry more weight here.
A sacrifice of a living creature on this altar will cure any magical curses or magical diseases of the celebrants on a 1-in-6 chance.
2 Cage
A prison, a hanging gibbet, a jail designed to constrain its prisoners. What crimes could they have committed to be bound to such a fate? Are they imprisoned unjustly or are there sins on their conscience that cannot be forgiven?
Example: A hanging cage made of thin sticks lashed together with leather cords. The door is fastened simply with a knot of herb (monkshood). The cage looks like you could kick it apart easily. Inside, an old man named Zacchaeus claims to be brought here as food for vampires and begs to be let out.
In truth, Zacchaeus is a werewolf. The monkshood (otherwise known as wolfsbane) keeps him so weak he cannot break the bars.
3 Circle of Power
Sites of power constructed where the leylines of the dungeon converge. These circles are designed as gates between the realm of flesh and the far realms--either to seal outside entities out or beckon such entities in. They are dangerous things, whose magic is more than any single mortal sorcerer can master.
Example: A glyph written on the floor crackles with obvious magical energy. The glyph is surrounded by five, five-pointed pyramidal stones. The side of each stone is marked with runes that read "AB-RA-KA-DAB-RA".
If the PCs step onto the glyph without changing the set up, they are teleported to a deeper level of the dungeon turned inside out (instant death, no save). The glyph must be made harmonized by turning pyramidal stones so the runes facing the inside of the glyph read "Abrakadabra." This word can start from any stone, but should proceed in order until every syllable is used sequentially in a clockwise manner. When this is done, the teleportation magic is safe to use.
4 Elevator
Elevators are platforms or chambers that move around the dungeon (vertically, horizontally, or in stranger ways). Different levels of the dungeon may be connected by elevators that need to be activated.
Example: The PCs step into the bottom of a deep pit. A colossal chain ending in a huge hook dangles from an unseen place high above. A giant earthworm is pierced by the hook, wiggly feebly. If the PCs manage to make a significant pull on the chain (requiring a total 18 Strength points), the giant at the top of the pit pulls hook and chain up to the upper level. He's not interested in the PCs and will discard them at this upper level as being "under his limit."
5 False Tomb
There are tombs down here. But there are also false tombs intended to baffle and punish grave robbers. These facades obscure the true burial chambers behind secret doors and deadly traps.
Example: A mosaic depicts a bull-headed man holding a scale with a feather and a heart. Beneath it, two doors. Ancient writing on the wall (when translated) reads: "The just enter on the left to pass to paradise. The unjust enter to the right to meet their punishment."
The doors both lead to the same small chamber. About five seconds after the doors are opened, a two-ton block drops into the small chamber, crushing anyone within who doesn't succeed in a Dexterity save (or equivalent) to dodge back into the false tomb.
6 Fountain
Fountains in dungeons are often enchanted as the water flows past veins of mithril. Drinking or bathing or dipping items into the fountain activates their enchantments.
Example: A merry face is carved on the outlet of the spring where this fountain flows. The face speaks simple phrases, welcoming travelers to drink from its waters.
Drinking from the waters causes mild euphoria and hallucinations. If under any persistent negative enchantments, geasa, mind control, or similar effects, characters who drink the water are allowed a new saving throw to attempt to overcome them. However, characters who have drunk from the water always move last in initiative and cannot cast spells due to consistent giggling interrupting their incantations. This effect lasts until the PC sleeps.
7 Fungus
There are strange growths in the depths of the earth where the sun has never shone. Fungi, mushrooms, and molds bloom in dark places, often with unwholesome and uncanny effects.
Example: A circle of yellow mushrooms with a little mouse inside. As the PCs watch, the mouse passes the circle of mushrooms and becomes a stirge, who flaps a few times before learning the trick of its wings and then flies away.
If the PCs step over the edge of the mushroom circle, they are transformed into a random creature. Roll for a random page on your Monster Manual. If there are multiple monsters on that page, let the player choose between them.
8 Hearthfire
This place looks safe enough for now. Here, other adventuring parties have encamped. An ember of their fire remains. Light it again to kindle some hope in this dark place.
Example: A small shrine with a campfire in which a ruined sword has been driven. Those who camp here regain full HP during a night's rest.
9 Idol
The Underworld contains giant idols of strange gods. Some say they were raised by ancient troglodytes. Some say they were gods that crawled into the veins of the earth and became fossils. In either event, there is still some strange power in these colossi.
Example: A giant statue of a seated devil with gemstone eyes sits. It holds a huge brazier of coals. Clerics can hear the statue whispering obvious blasphemies.
Attempting to pry out the idol's gemstone eyes causes the idol to tip the brazier over, pouring liquid fire into the room. The room's floor becomes lava. The would-be thieves are trapped on the statue with no obvious way out.
10 Lava Flow
Lava is the lifeblood of the earth. It flows, here, in the earth's veins. It is, of course, death for adventurers.
Example: Lava cascades from an unseen height like a waterfall. It flows into cut channels which feed into a forge's fire. Nearby, an anvil sits. The heat is unbearably intense.
The PCs cannot approach unless they have some defense against the heat. If they have fire resistance or similar, PCs can spend time here to transform mithril ingots into +1 weapons.
11 Library
Books and scrolls are hoarded by scholars, lore-masters, and wizards. Libraries house books that are written on papyrus, vellum, and wax tablets. Many things that are forgotten on the surface can be found trapped in letters here. However, it takes time to carefully pour over the tomes here, translating the antique dialects and shepherding the fragile pages.
Example: The necromancer Crabbe made the Library of Heads: mummified heads sitting on concentric circular shelves in a circular room. If you pick up the heads and blow through their neck hole, they begin to recite their life's story in their native tongue. There are 102 heads here. Many have nothing interesting to say to an adventurer. A few hold some esoteric knowledge worthy of a researcher in a niche subject. At least three were rival sorcerers who speak eloquently about their forays into astral space.
12 Machine
Mechanisms made by ancient hands, the purpose and the logic of which are not known. Some machines are malfunctioning, producing imperfect results. Some are broken, but can be fixed (though not understood) by replacing an obvious part or providing a power source. Some work perfectly, but exactly what they do and why is beyond mortal ken.
Example: The workings of the Unmaking Machine are hidden inside its body, which resembles a 40' x 40' x 40' Borg cube.
The first time the Unmaking Machine is encountered by the PCs, there is a single, six inch, cube-shaped section missing from the left side of the cube. This missing cube can be found elsewhere in the dungeon and inserted like a key into it. The machine thereafter begins to function.
Once repaired, the only interface with which to operate the machine are two apertures, both square holes exactly 13" in diameter, both on the cube's "front." When an item is placed into the upper hole, it slides into the darkness as if drawn in by a hand. The cube emits a series of grinding sounds. Then, the component construction materials of the item issue out from the lower hole.
For example, if a sword was entered into the top hole, the cube emits the following: an ingot of iron, small cubes of trace minerals involved in embellishment, a strip of leather and a solid block of wood (both from the hilt), a dollop of animal-based glue, and a single droplet of oil (residual from maintenance).
If an item is jammed into the lower hole, it comes out of the top hole terribly mangled.
13 Magic Wall
Magical barriers may be raised to gate certain sections of a dungeon. These could be magical force fields or walls made of esoteric energies, such as walls of fire or walls of ice. The key to these walls are almost always magical. Often, the artifact or structure generating the wall needs to be disabled.
Example: An archway of skulls bifurcates a room. The keystone skull once belonged to a giant bird. A malicious presence haunts the bird skull, whose evil will allows only those who bear the tokens of its master the Pigeon King to pass.
This is not a physical barrier but a mental command screaming DO NOT FUCKING ENTER. It cannot be resisted by any sentient, living creature. Arrows and spells may pass under the archway.
The keystone skull's evil will can only work on creatures it can see. Blinding the skull (with a Flare spell) or sneaking past while invisible will also allow passage.
14 Merchant
Rule of Acquisition 34: War is good for business. Adventurers are a desperate sort, and their pockets are often weighed down with grave goods, golden idols, and other ill-gotten gains. Shrewd merchants have learned that you can make more selling a single candle to an adventurer in a dark dungeon than you can selling candles to a cotter's wife all year. That said, most merchants you find in a dungeon aren't the sort to go in for a brick-and-mortar business.
Example: Grinnin' Grimnir is a goblin who hauls around a sleigh filled with assorted goods. He always sells balls of twine (1 gold), candles (5 gold), torches (10 gold), daggers (20 gold), and iron rations (30 gold). He also has 10 items from
this table every time you encounter him. Put him on your random encounter table.
Grinnin' Grimnir is protected by a curse. Anyone who kills him will be cursed with vile luck for a year. For an adventurer, this spells certain death. Those who try to run away from the bad luck in remote townships undergo so much trauma they eventually resemble a little, constantly giggling goblin. They are eventually seized with the strange compulsion to load up a sleigh and start a little trade in the local dungeon.
15 Mirror
Magical mirrors create aberrant reflections of the real world. They sometimes serve as traps, creating doppelgangers of the PCs. They also serve as portals, perhaps to an alternate dimension or pocket plane. These also might be the focal piece of a puzzle, where the mirror must reflect a ray of light in a different direction.
Example: A hall of twelve mirrors, three of which bear the frozen visage of an adventurer and three of which are broken. Those who look into an empty mirror see their own reflection frozen there.
PCs who look into an empty mirror create a "save state." At any point, they can choose to reset their bodies directly to this point - same EXP, same HP, same stats, etc. This must be done consciously, i.e., before they are unconscious or dead. When this ability is activated, the image disappears from the mirror and the mirror breaks.
16 Oubliette
An oubliette is where you put someone to forget about them. Accessed only by a trapdoor, these deep pits serve as prisons for those now long abandoned.
Example: This oubliette contains two skeletons: one of a human (wearing the tattered remains of a once fabulous gown) and one of a dwarf. The human skeleton has tooth marks indicative of a cannibalistic end. Written on blood on the wall is a crude map of the dungeon. Careful inspection of the map reveals a small secret room.
Those who find the secret room find it empty except for an unmounted door. This is a magical door that can be hammered into any wall to create a permanent door there.
17 Painting
Paintings, tapestries, frescoes, and mosaics provide more than simple dungeon decoration. They often hide secrets, carry an enchantment, or provide important context to nearby puzzles.
Example: A framed painting of a door with no knob. Elsewhere in the dungeon are magical paints. Painting a knob onto the door will turn the painting into a functioning secret door.
18 River
Delvers beware! Underworld rivers notoriously have uncanny properties, and drinking even a drop of their water will rob you of your memories, plunge you into eternal sleep, cause ceaseless weeping, or deliver other terrible curses.
Underground rivers initially serve as barriers that restrict travel--how will the adventurers get across the rushing river? Once the appropriate vehicles or tools are discovered, these rivers can actually serve as connective arteries to deeper sections of the dungeon. Boats can be used to travel the rivers to hitherto inaccessible sections.
Example: The River Phlegethon looks like a normal river but the water is acidic, earning it the nickname the "River of Fire." It exudes a noxious, sulphurous scent. Any normal item submerged into the waters is quickly destroyed.
If the PCs can persuade Iago the Lion-Turtle to take them onto his back, he can wade and withstand the waters of this river, and ferry them to the other side.
19 Sepulcher
Past the false tombs, sepulchers entomb the dead. Sometimes these dead are restless, sometimes they have are withered away to bones. Adventurers low in scruples and funds often loot these sepulchers in hopes of grave goods, but often find traps and curses instead.
Example: A sarcophagus whose stone lid depicts a snake-headed human. The lid is massively heavy and can only be moved with a combined 30 Strength; tools like a ten-foot pole used as a lever add +5 Strength, but usually snap the lever unless it is unusually sturdy. Inside, a mummy.
The mummy is just a normal mummy, not an undead. It does carry a disease, however. If you handle the body directly without gloves, save vs disease to avoid contracting mummy rot.
The wrappings around the mummy contain ancient spells. Unwrapping the mummy yields two "scrolls" of random 5th level spells.
20 Statue
These graven images bear the semblance of ancient kings, heroes, and mythological figures. They reflect the culture of those who shaped them, and provide clues to their creator's world view with regards to the local dungeon environment. A recent poll of dungeon delvers found that 70% of puzzles incorporated statues in some way.
Example: A three-faced statue of the elven Tripartite - the Maiden, the Mother, and the Crone - stands in the middle of a triangular room. Examination of the statue reveals scratch marks on the floor near its base, indicating the statue has been turned from its original position.
Two of the walls of the room are decorated with mosaics. One bears a crescent moon. One bears a white circle. The third wall is blank.
If the statue is turned so that the face of the Maiden is turned towards the crescent moon, the face of the Mother is turned towards the white circle, and the face of the Crone is turned towards the blank wall, the blank wall will become a misty portal that will teleport the party to a new location.
21 Throne
The thrones of the former rulers of the Underworld still contain some power within them. Those who sit on them are often given a measure of control over some dungeon feature or a special awareness of a facet of the Underworld. However, thrones often possess magical curses or traps laid on them to ensure only the worthy sit upon them.
Example: At the top of a pyramid of stairs, each spaced too wide for the human gait, is a colossal throne. It is covered in dust, mice skeletons, and owl droppings. The back of the throne is sculpted like spread owl wings. The arms of the throne each depict a closed eye.
Sitting on the throne with a light source causes the light source to suddenly flare and go out. The victim must pass a saving throw or be blinded until after they next sleep.
Those who sit on the throne find their hearing greatly improved. They have blindsight for as long as they sit on the throne. Immediately, they hear the whistling of wind through a crack in a secret door on the north wall. Additionally, they hear whispering far above them. For each dungeon turn they spend concentrating, they hear one rumor about the current dungeon level.
22 Waterwheel
Waterwheels harness the power of the strange rivers of the Underworld. Adventurers may find the state of the dungeon changed if a waterwheel is stopped or started.
Example: The flow of the river is split into three waterfalls by a series of locks and dams controlled by levers inside the dungeon. When the water turns the northern waterwheel, the colossal door to the necropolis is raised. When the water turns the eastern waterwheel, the lamps inside the Castle of Crossed Destinies are lit, allowing adventurers to forego carrying their own torches. When the water turns the western waterwheel, the bridge extends from the castle towards the City of Ruin. Only one waterfall can flow at a time.
23 Well
Wells in the Underworld contain bizarre things: wine, treacle, oil, pudding. Almost anything but water. Moreover, wells often have some denizen who lives off their contents, either dwelling at the bottom of the well or guarding it from interlopers.