Wheel, the World Tree, and the World Axis, but you
can create or adapt whatever model works best for the
planes you want to use in your game.THE GREAT WHEEL
The default cosmological arrangement presented
in the Player's Handbook visualizes the planes as a
group of concentric wheels, with the Material Plane
and its echoes at the center. The Inner Planes form
a wheel around the Material Plane, enveloped in the
Ethereal Plane. Then the Outer Planes form another
wheel around and behind (or above or below) that one,
arranged according to alignment, with the Outlands
linking them all.
This arrangement makes sense of the way the River
Styx flows among the Lower Planes, connecting
Acheron, the Nine Hells, Gehenna, Hades, Carceri, the
Abyss, and Pandemonium like beads on a string. But it's
not the only possible explanation of the river's course.THE WORLD TREE
A different arrangement of planes envisions them
situated among the roots and branches of a great cosmic
tree, literally or figuratively.
For example, the Norse cosmology centers on the
World Tree Yggdrasil. The three roots of the World
Tree touch the three realms: Asgard (an Outer Plane
that includes Valhalla, Vanaheim, Alfheim, and other
regions), Midgard (the Material Plane), and Niflheim
(the underworld). The Bifrost, the rainbow bridge,
is a unique transitive plane that connects Asgard
and Midgard.
Similarly, one vision of the planes where the deities
of the Forgotten Realms reside situates a number of
celestial planes in the branches of a World Tree, while
the fiendish planes are linked by a River of Blood.
Neutral planes stand apart from them. Each of these
planes is primarily the domain of one or more deities,
though they are also the homes of celestial and fiendish
creatures.
THE WORLD AxiS
In this view of the cosmos, the Material Plane and its
echoes stand between two opposing realms. The Astral
Plane (or Astral Sea) floats above them, holding any
number of divine domains (the Outer Planes). Below
the Material Plane is the Elemental Chaos, a single,
undifferentiated elemental plane where all the elements
clash together. At the bottom of the Elemental Chaos is
the Abyss, like a hole torn in the fabric of the cosmos.
OTHER VISIONS
As you build your own cosmology, consider the
following alternatives.
The Omniverse. This simple cosmology covers the
bare minimum: a Material Plane; the Transitive Planes;
a single Elemental Chaos; an Overheaven, where good-
aligned deities and celestials live; and the Underworld,
where evil deities and fiends live.
Myriad Planes. In this cosmology, countless pla nes
clump together like soap bubbles, intersecting with each
other more or less at random.
CHAPTER 2 I CREATING A Mt.:LTI\ ERSE
The Orrery. All the Inner and Outer Planes orbit the
Materi a l Plane, exerting greater or lesser influence on
the world as they come nearer and farther. The world of
Eberron uses this cosmological model.
The Winding Road. In this cosmology, every plane is
a stop along an infinite road. Each plane is adjacent to
two othe rs, but there's no necessary cohesion between
adjace nt planes; a traveler can walk from the slopes of
Mount Celestia onto the slopes of Gehenna.
Mount Olympus. In the Greek cosmology, Mount
Olympus stands at the center of the world (the Material
Plane), with its peak so high that it's actually another
plane of existence: Olympus, the home of the gods. All
the Greek gods except Hades have their own domains
within Olympus. In Hades, named for its ruler, mortal
souls linger as insubstantial shades until they eventually
fade into nothing. Tartarus, where the titans are
imprisoned in endless darkness, lies below Hades. And
far to the west of the known world in the Material Plane
are the blessed Elysian Fields. The souls of great heroes
reside there.
Solar Barge. The Egyptian cosmology is defined by
the daily path of the sun-across the sky of the Material
Plane, down to the fair Offering Fields in the west,
where the souls of the righteous live in eternal reward,
and then beneath the world through the nightmarish
Twelve Hours of Night. The Solar Barge is a tiny Outer
Plane in its own right, though it exists within the Astral
Plane and the other Outer Planes in the different stages
of its journey.
One World. In this model, there are no other
planes of existence, but the Material Plane includes
places like the bottomless Abyss, the shining Mount
Celestia, the strange city of Mechanus, the fortress of
Acheron, and so on. All the planes are locations in the
wodd, reachable by ordinary means of travel-though
extraordinary effort is required, for example , to sail
across the sea to the blessed isles of Elysium.
The Otherworld. In this model, the Material Plane
has a twin realm that fills the role of all the other planes.
Much like the Feywild, it overlays the Material Plane
and can be reached through "thin places" whe re the
worlds are particularly close: through caves, by sailing
far across the sea, or in fairy rings in remote forests. It
has dark, evil regions (homes of fiends and evil gods),
sacred isles (homes of celestials and the spirits of the
blessed death), and realms of elemental fury. This
otherworld is sometimes overseen by an eternal city, or
by four cities that each represent a different aspect of
reality. The Celtic cosmology has an otherworld, called
Tfr na n6g, and the cosmologies of some religions
inspired by Asian myth have a similar Spirit World.PLANAR TRAVEL
When adventurers travel to other planes of existence,
they undertake a legendary journey that might force
them to face supernatural guardians and undergo
various ordeals. The nature of that journey and the trials
along the way depend in part on the means of travel, and
whether the adventurers find a magic portal or use a
spell to carry them.