Places in Limbo: The Universal Encyclopedia (D&D/Planescape)

THE UNIVERSAL ENCYCLOPEDIA
All things are retained in the Universal Encyclopedia. The Encyclopedia looks like a tower of arches on a spiraling, ramped pathway. It is on every plane and there are many ways in, but the primary entrance is on Limbo, in the Funeral of Logos, amid plains of failing words that burrow into the skin like rot grubs and burst novel and useless vocabularies from your corpse, whose moldy paper hills and drab watercolor trees are stalked by bands of thought thieves and of course, the Jabberwocky.

The Encyclopedia is a bit like a pin piercing the planes, and like the proverbial pin, is nearly impossible to find until you step on it. 

Inside, it's stacks and shelves and cages and cases. Marble floors, columns, walls. Water runs down (sometimes up) most walls in sheets from somewhere far above (theory: it's coming from "Dam, Broken" or maybe its "Lake" or "Ocean"). There are endless rooms and cubbies and reading nooks, stairs up and down. If there is top or bottom, it hasn't been sounded.

The use of fire and lanterns is strictly prohibited and the halls are unlit but for the holding cages, whose lights blink and fluid glows softly (treat as a candle).

There are books but also scrolls and tablets and nearly every other media on which words may be printed. Some writing has been transcribed from older texts into newer media - there are, for example, holographic lexicons of Sumerian cuneiform - and other clever or desperate or capricious lexographers have recorded languages not yet spoken in places not yet made on scrimshaws. There are animals in cages and animals roaming about and everywhere is cluttered with the trophies of Nimrod's glory days (strange animals, stuffed). Every kind of thing is there, literally (people that lived, people that will live all of them sleeping on all planes and in all ways, unable to wake or do anything while in the Encyclopedia), everything but magic.

Accordingly there aren't spell books here, because magic is selfish and secretive and not a part of anything/something else entirely. Wizards could still probably find spell books because Wizard's minds are a mess.

Everything is cataloged, but Nimrod (the guard/docent/custodian) can't remember where the catalog is (it is, of course, under "C").

GOD LOCUS
The Universal Encyclopedia ("Oh, Ark of Knowledge, Oh Sum of Forms") is worshiped by academic-clerics, priest-librarians and mathologizers and idolized by knowledge pornographers. Worship grants clerics either Knowledge or Trickery Domains. 

DIEGITIC LICH
Entries in the Universal Encyclopedia are diegetic lichs: their form may be carried out (borrowed) but their essential substance remains in the Encyclopedia. Destruction of an Entry requires destruction of the idea/substance of the Entry.

Destroying anything in the Encyclopedia removes it from all existence everywhere for all time until someone else invents it again. Destroying things like hunger and hatred and evil never do much as we just immediately re-invent them. Pacifist-terrorists, Chaos Catholics, revolutionaries, and other persons and peoples intent on reality schism still try, from time to time, and their corpses litter the hills of Limbo.

Cleaver terrorists will hire saboteurs to destroy apex predators or a single person in an attempt to destabilize ecosystems or powers.

There are, of course, a great many things in the Encyclopedia that destroy ideas/substances either purposefully or as a byproduct - fascist logic engines, parasites that devour ideas using language or other ideas or art as vectors, a machine that makes new things by crushing up old things completely and entirely. 

BORROWING
When attempting to carry an Entry out of the Encyclopedia, the borrower finds themselves drawn inevitably to the exit guarded by the Encyclopedia's guard: Nimrod. The exact mechanism is any mechanism that works, usually through a kind of suggestion  or mass illusion or, if those fail, the Encyclopedia just shuffles its page-floors so you wind up at Nimrod's exit.

The rule of the Encyclopedia, as is clearly stated in all languages on the walls, column, floors and molecules in the primary entrance/exit hall and, for the ease of the visitor, in all possible sizes, colors and spectrum as well as in thoughts, ideas, songs and images, require three things for the borrowing of an item:

1. a deity's permission
2. an item of equal value (meaning: you have to create a new idea or a new kind of thing of equal value [according to Nimrod] to be able to take the thing you want with you)
3. one must not acknowledge in any way the thing one is borrowing (cannot speak to, cannot look back at) while still on Limbo

(there used to be two rules but Limbo didn't like people taking potshots with just-borrowed cross-planar mortars or releasing loaned planar mites into its flesh, so it poked through truth and fact and added a third rule)

IT ROTS AND THESE HALLS ARE FULL OF DUST
Time passes and entropy reigns and the lich fails and an Entry must be restored by its substance. Husks of Entries, empty book-forms like brittle chrysalis crunch underfoot and the leathery shed skin and rotten guts of the animals and people lay at the feet at the Entry's current incarnation.

Dust reaches the waist in places, often at least the ankle. At its deepest, the dust has formed sediment and even ossified into rocks.

These leavings, being the ruined diegesis of a pure form, are a sort of incomplete, nearly universal language, the near total expression of all forms. 

DUST OF TONGUES
per snort, 30% chance its useful, 70% chance its obscure words or conjugations of irregular verbs or morphemes and phonemes fallen out of use or illogical combinations of idea-flesh-sound, and DC 20 Wis Save or spend an hour vomiting words from your own language (you're disadvantaged while communicating for the remainder of the session)

SLUDGE OF TONGUES
may be smeared onto a text to make it legible in your language (this literally changes the language and can deform the original meaning and may ruin magical texts (10% chance per level of magic as well as relative complexity). Can be used on the tongue or dropped on the eye to have the same effect as the Dust of Tongues (DC 25 Wis save required, however). Used by certain torturers, spies and demons to concoct Gabber (see below).

ROCK OF TONGUES
May be used as an ebenezer/arcane focus for casters. Can be crushed to have the same effect as the Dust of Tongues. Swallowing a fist-sized rock causes one to be proficient in any language relatively common language and have advantage when trying to read or communicate in an obscure or dead or magical one and when making any History or Arcana check. After eight hours, a massive headache (exhaustion level 1) and disadvantaged when communicating for the remainder of the session (at least).

Gabber (DC 15/20 Con Save poison)
Weak Gabber forces the user to speak without stop for d4 days. There is an attending risk of starvation and dehydration, and, as the victim cannot sleep, exhaustion is guaranteed. The victim has control over what they say, however.

Stronger, lethal Gabber makes speaking sublimates all bodily functions to speaking. Everything will try to communicate meaning, hands signing, toes pointing. Death is usually cause by asphyxiation - speaking without trying to breather, the victim gasps like a fish suffocating.

OTHER ITEMS AND MONSTERSThe Voice of Nimrod
A recurve bow 5' tall, unstrung and snapped in half, requiring attunement, STR 12 to use. Any arrow shot from this bow strikes to the truth in addition to whatever other damage or effect it causes. The first blow, dispelling any one illusion (DC 30 dispel), the second any one lie (DC 25 command to not not lie) and the third any planar distortion (displacement/phasing/brings ethereal and astral beings into this plane, gives flesh to the incorporeal).

to repair:  the gut of librarian-wyrm unkilled (ancient dragon) to re-string and a set of tools from a divine bowyer and a dwarven smith to repair its delicate mechanisms and rune-filigrees. 

The Foot of Nimrod
Tarnished, now used as a bed, once a grand sky-steel chariot. Once hitched, moves at great speed for twice as long without tiring mounts, can be used to fly at the same speed (which will freak out terrestrial mounts) but is built for a being greater than you (at disadvantage until attuned and without STR 18). 

The Night Crown
An Assyrian-style crown looking like a pale gold cylindrical tower. The first crown worn by a mortal, composed of the night sky, a moon and several stars. Inherently magical, an ancient symbol of status and respect in all outer planar courts. Extremely cold. 

Gorm & Glot
There is a guard dog in the Encyclopedia (the Gorm) and a parasite eating its diegetic lichs like a bookworm (the Glot). The Gorm is never around because it's chasing the Glot. Both will try to recruit help if anyone looks able.

More on them later.

attribution: Pieter Bruegel the Elder