Blood and Jazz
The major planes of existence are connected to one another in a pattern that is often allegorically likened to a wheel with many spokes and a hub, in order to simplify and aid in visualizing the complex spatial geometries and magic involved for practical purposes. Some scholars prefer to visualize it as akin to a massive rotating disk of stars known as a “galaxy”, but this model is not well-liked in Ërdin, where astronomical bodies such as galaxies are less familiar to the general public due to the rarity of sightings of galaxies through Boccob’s Veil.
The “axel” of the Great Wheel is a great spire of apparently infinite length that runs through the center of a plane known as the Outlands—the Great Wheel’s “hub”. The “turning” of the Great Wheel about this spire generates magic in much the same way that a physical wheel generates centripetal force, and like an eye at the center of a hurricane, the space around the spire’s immediate vicinity acts as a dead magic zone. One end of the spire, considered the “northern” end, is home to Sigil, an enormous ring-shaped floating city built with its eyelet about the spire, where some mysterious deities and other beings of incomprehensible power and intelligence (such as the infamous Lady of Pain) make their abode if they have nowhere else in the Great Wheel to call home.
A ways “north” of the Outlands is the Plane of Positive Energy, bright as all the stars in all the planes combined; some ill-understood crucial ingredient for life trickles southward from this plane into all others, usually as a component of the chemical element hydrogen, channeled into photosynthesized sunlight and chemosynthesized hydrogen and hydrogen sulfide and thence into all organisms that consume said photosynthetic plants or chemosynthetic bacteria (though also in much smaller quantities by the direct channelling of positive energy by clerics). “South” of the Outlands is the Plane of Negative Energy, even less understood than its opposite, which fuels the equivalent processes of unlife.
Orbiting just outside the boundaries of the Outlands are the countless multitudes of Material Planes, each with an associated Ethereal Plane and Plane of Shadow created by the brightness of the Plane of Positive Energy and the darkness of the Plane of Negative Energy. Orbiting just outside the Material Planes are the four Elemental Planes of Air, Fire, Earth, and Water, each of which flow into the Material Planes in much the same way as do the Planes of Positive and Negative Energy, forming the abiotic base of Material Plane existence.
Beyond the Elemental Planes, orbiting at the very rim of the Great Wheel, are the sixteen Outer Planes. These planes are where the godlike outsiders dwell and where the spirits of the dead are “thrown” by the spinning of the Great Wheel once they become unmoored from their physical bodies. They are organized by the alignments of the dominant deities that dwell within them, as follows:
The planes thus far described all orbit within a medium known as the Astral Plane, which is technically not a plane but rather is the void between planes. Beyond the rim of the Great Wheel lies the Far Realm, where worlds and beings beyond the comprehension of even deities reside, pursuing unfathomable goals for which the beings of the Great Wheel are largely and mercifully irrelevant.
A potentially helpful map for the confused planeswalker: