The Abyss features an endless variety of evil - layer upon layer, world upon world in which the very air, earth, and water reek of toxic corruption. The home of Toril's demons is as varied as the demons themselves; with each layer offering a unique landscape apparently designed to inflict as much pain and torment as possible on those who pass through it.
Unlike most of Toril's planes, the Abyss is not a single common area with divine realms branching from it. Rather, it is an apparently infinite number of layers, each with its own unique characteristics. No central "trunk" or neutral area connects these realms. Travelers might enter any layer of the Abyss, and they might encounter portals there to any of the other layers. Each layer is coterminous to some number of others, but these relationships seem to change continually, like a mass of bubbles settling and shifting around each other. The only constant in this chaotic jumble is the presence of the adjacent Blood Rift, where the demons fight their mortal enemies, the devils.
The proximity of Blood Rift to both the Abyss and the Nine Hells allows the demons to make unceasing war upon the devils. While Blood Rift always touches a particular layer of the Nine Hells (the first layer, called Avernus), the ever-shifting nature of the Abyss brings different layers into proximity with Blood Rift at different times, allowing the demons to hung new forces to bear constantly in the so-called Blood War.
The Abyss has the following traits.
- Normal gravity. Some layers of the Abyss feature different gravity traits.
- Alterable morphic.
- Mixed elemental and energy traits. These traits vary widely from layer to layer. In the Abyss as a whole, no one element or type of energy constantly dominates, though a given layer may have a dominant element or energy, or a mixture of two or more.
- Mildly chaos-aligned and mildly evil-aligned.
Various layers of the Abyss include portals to the Demonweb Pits, Beshaba's realm in the Barrens of Doom and Despair, Hruggek's realm in Clangor, the realm of Urdlen in Hammergrim, and the Fugue Plane. In addition, portals frequently open to connect the Abyss with Deep Caverns and Fated Depths. The spring of the River of Blood is said to lie somewhere in the Abyss, and tributaries flow from many Abyssal layers to feed its putrid waters. The River of Blood links the Abyss to most other fiendish planes.
First and foremost, the Abyss is the home of the demons. Any demon from the Monster Manual or any other source dwells in the Abyss. Other denizens of the Abyss include bodaks, night hags, and nightmares, Abrian, Abyssal ghoul, bloodthorn, demonflesh golem, ironmaw, living holocaust, Abyssal ant swarm, bloodfiend locust swarm, varrangoins (all), vorr, vultivor (canomorph).
Abyssal Petitioners: When demons steal souls from the Fugue Plane and bring them to the Abyss, those souls become petitioners called manes. A mane has pale white skin, cruel claws, sharp teeth, sparse hair, and white eyes. Often, maggots visibly squirm through its bloated flesh. Manes that survive for many years are sometimes "promoted" to lesser demon types, though they retain no memory of their former lives. Manes have the following special qualities.
Additional Immunities: Electricity, poison.
Resistances: Acid 10, fire 10.
Other Special Qualities: Acidic vapor, no planar commitment.
Acidic Vapor (Su): When a mane is slain, it discorporates into a cloud of noxious vapor. Every creature within 10 feet of a slain mane must make a successful DC 20 Reflex save or take 1d6 points of acid damage.
No Planar Commitment (Ex): Unlike most other petitioners, manes can leave the plane they call home.
Features Of The Abyss
Use the Random Abyssal Layers, table on page 161 of the Dungeon Master's Guide to generate the characteristics of any Abyssal layer.
The Abyss has no divine realms, and no true deities make their homes there. However, a great many demon princes - probably as many as there are layers of the Abyss - vie for power and territory on this plane. Prominent demon princes include Demogorgon, Eltab, Yeenoghu, Orcus, Graz'zt, Baphomet, and Kostchtchie, most of whom are described in Book of Vile Darkness.