The Planes of Existence

The cosmos teems with a multitude of worlds as well as myriad alternate dimensions of reality, called the Planes of Existence. It encompasses every aspect of Gaia, all within the relatively mundane realm of the Material Plane. The Planes of Existence in Gaia came about from the Founding, during the Creation, and contain the raw magics and elements that form life as we know it today. Born from a violent and intense war between the Titans and the First Gods, these planes form reality, and give shape to the otherwise amorphous and vacuous Cosmos.

Each plane is separated by a Divine Gate, or Wall, that requires immense energy and magic to travel through. These delicate barriers are integral to preventing the collapse of all the planes into the Material Plane, forever marring and altering life as we know it. The Divine Gates are studied extensively in order to better understand the origins of Gaia, as well the very magics that can be harnessed by those skilled enough. The far-reaching planes require the most magical energy to pierce through, with openings being small and short-lived. It is thought that the gateway from lesser planes to higher planes is easier to open than vice versa, but that has not stopped many from trying.

Some of these planes are theorized to exist, with research and formulations merely requiring their existence for completeness sake, thus, many of them are completely unexplored.

Transitive Planes

The Ethereal Plane and the Astral Plane are called the Transitive Planes. They are mostly featureless realms that serve primarily as ways to travel from one plane to another. Spells such as etherealness and astral projection allow characters to enter these planes and traverse them to reach the planes beyond.

Inner Planes

The Inner Planes surround and enfold the Material Plane and its echoes, providing the raw elemental substance from which all the worlds were made. The four Elemental Planes -- Air, Earth, Fire, and Water -- form a ring around the Material Plane, suspended within the churning Elemental Chaos.

At their innermost edges, where they are closest to the Material Plane (in a conceptual if not a literal geographical sense), the four Elemental Planes resemble a world in the Material Plane. The four elements mingle together as they do in the Material Plane, forming land, sea, and sky. Farther from the Material Plane, though, the Elemental Planes are both alien and hostile. Here, the elements exist in their purest form -- great expanses of solid earth, blazing fire, crystal-clear water, and unsullied air. These regions are little-known, so when discussing the Plane of Fire, for example, a speaker usually means just the border region. At the farthest extents of the Inner Planes, the pure elements dissolve and bleed together into an unending tumult of clashing energies and colliding substance, the Elemental Chaos.

It is theorized that there once were more elemental planes in the Inner Planes, but they were devoured or destroyed during the Founding.

Outer Planes

If the Inner Planes are the raw matter and energy that makes up the multiverse, the Outer Planes are the direction, thought and purpose for such construction. Accordingly, many sages refer to the Outer Planes as divine planes, spiritual planes, or godly planes, for the Outer Planes are best known as the homes of deities.

When discussing anything to do with deities, the language used must be highly metaphorical. Their actual homes are not literally "places" at all, but exemplify the idea that the Outer Planes are realms of thought and spirit. As with the Elemental Planes, one can imagine the perceptible part of the Outer Planes as a sort of border region, while extensive spiritual regions lie beyond ordinary sensory experience.

Even in those perceptible regions, appearances can be deceptive. Initially, many of the Outer Planes appear hospitable and familiar to natives of the Material Plane. But the landscape can change at the whims of the powerful forces that live on the Outer Planes. The desires of the mighty forces that dwell on these planes can remake them completely, effectively erasing and rebuilding existence itself to better fulfill their own needs.

Distance is a virtually meaningless concept on the Outer Planes. The perceptible regions of the planes often seem quite small, but they can also stretch on to what seems like infinity. It might be possible to take a guided tour of the Nine Hells, from the first layer to the ninth, in a single day--if the powers of the Hells desire it. Or it could take weeks for travelers to make a grueling trek across a single layer.

The most well-known Outer Planes are a group of sixteen planes that correspond to the eight alignments (excluding neutrality) and the shades of distinction between them.

Upper and Lower Planes

The planes with some element of good in their nature are called the Upper Planes. Celestial creatures such as angels and pegasi dwell in the Upper Planes. Planes with some element of evil are the Lower Planes. Fiends such as demons and devils dwell in the Lower Planes. A plane's alignment is its essence, and a character whose alignment doesn't match the plane's experiences a profound sense of dissonance there. When a good creature visits Elysium, for example (a neutral good Upper Plane), it feels in tune with the plane, but an evil creature feels out of tune and more than a little uncomfortable.

Demiplanes

Demiplanes are small extradimensional spaces with their own unique rules. They are pieces of reality that don't seem to fit anywhere else. Demiplanes come into being by a variety of means. Some are created by spells, such as demiplane, or generated at the desire of a powerful deity or other force. They may exist naturally, as a fold of existing reality that has been pinched off from the rest of the multiverse, or as a baby universe growing in power. A given demiplane can be entered through a single point where it touches another plane. Theoretically, a plane shift spell can also carry travelers to a demiplane, but the proper frequency required for the tuning fork is extremely hard to acquire. The gate spell is more reliable, assuming the caster knows of the demiplane.