Great Wheel
The Great Wheel is the traditional term used to refer to the multiversial cosmology of Dungeons and Dragons. Invented for Advanced Dungeons & Dragons 1st edition, it served through AD&D 1e, AD&D 2e and D&D 3e, was replaced with the World Axis in 4e, and returned in a slightly altered form in 5e.
The Great Wheel is made up of a multitude of dimensions (called "planes") arranged into ever-increasing circles, radiating outward from the Prime Material Plane (the "mortal world"), hence its name. These are subdivided into the Inner Planes and the Outer Planes, but these are just the first of many subdivisions.
In the Great Wheel, the Demiplane of Dread, where the Ravenloft campaign setting takes place, is said to be located deep in the Ethereal Plane.
Inner Planes
The Inner Planes refers to the Prime Material Plane and all the other planes on its "side" of the Astral Plane. Denizens of the Inner Planes are often perceived as provincial, uneducated and backwards by those of the Outer Planes.
The Prime Material Plane is the "mortal world", the place which most closely functions as "reality". According to Spelljammer, the Prime Material is made up of a vast sea of flammable vapors called the Phlogiston, in which Crystal Spheres containing solar systems float like bubbles of reality.
The Ethereal Plane is a ghostly mirror of the Prime Material, and often regarded as the barrier between the Material and the Elemental Planes.
The Plane of Shadow is a mirror of the Prime Material in which darkness is the dominant metaphysical characteristic, creating a gloomy realm of dim light and utter darkness.
The Elemental Planes are considered the building blocks of the Prime Material, and consist of planes made up of a singular element in all its manifest forms, but interspersed with "cosmic flecks" of the other elements - for example, pockets of air or stone in the Plane of Water. Whilst the term can be used to refer to all element-related planes cohesively, it is most commonly used to refer to the four "primary" elemental planes of Earth, Air, Water and Fire. Other portions of the Elemental Planes are the Energy Planes (made up of Positive Energy, embodying life, and Negative Energy, embodying death), the Paraelemental Planes born of the conflux between the four primary elemental planes (Water/Earth: Ooze, Water/Air: Ice, Earth/Fire: Magma, Fire/Air: Smoke), and the Quasielemental Planes born of the conflux between the four primary elemental planes and the energy planes (Radiance, Crystal, Steam and Lightning for Positive; Void, Ash, Dust and Salt for Negative).
Astral Plane
The great divider between the Inner and Outer Planes. A gray, misty void.
Outer Planes
The Outer Planes refers to the seventeen planes that lie beyond the Astral Plane. Shaped by belief, these planes serve as the collective afterlife of the D&D multiverse, being the residence of gods, powerful spiritual beings, and the souls of the dead. They are heavily shaped by the 9-grid of character alignment, representing the conflux of the Four Powers of Law, Chaos, Good and Evil. As a result, the Inner Planes are broken into five overlapping subdivisions; the Upper Planes (realms embodying Good), the Lower Planes (realms embodying Evil), the Planes of Law (realms embodying Law), the Planes of Chaos (realm embodying Chaos) and the Planes of Balance/Conflict (realms embodying Neutrality).
Outer Planes are often divisible into multiple Layers, which represent specific aspects of a greater metaphysical concept. For example, the Beastlands embody the concept of "the wilderness", and are divided into three layers representing specific times of day (daytime, dusk/dawn, night) to accommodate diurnal, liminal and nocturnal life.
The complete list of the Outer Planes and their alignment resonance is:
- Celestia (Lawful Good)
- Bytopia (Lawful Good/Neutral Good)
- Elysium (Neutral Good)
- Beastlands (Neutral Good/Chaotic Good)
- Arborea (Chaotic Good)
- Arcadia (Lawful Good/Lawful Neutral)
- Ysgard (Chaotic Good/Chaotic Neutral)
- Mechanus (Lawful Neutral)
- The Outlands (True Neutral)
- Limbo (Chaotic Neutral)
- Acheron (Lawful Neutral/Lawful Evil)
- Pandemonium (Chaotic Neutral/Chaotic Evil)
- Baator (Lawful Evil)
- Gehenna (Lawful Evil/Neutral Evil)
- Hades (Neutral Evil)
- Carceri (Neutral Evil/Chaotic Evil)
- The Abyss (Chaotic Evil)
