Planes of Eberron
Eberron is the heart of the material plane. It is surrounded by the Ring of Siberys, a band of golden dragonshards. Beyond this, twelve moons orbit the world. To date, no creature from Eberron has ever explored the moons. None can say whether they are lifeless rocks or thriving worlds in their own right. Some sages believe that the moons are actually connected to the planes, or that they might even be physical extensions of the planes, but this remains a mystery.
The 13 Planes
The material plane is enfolded by thirteen planes of existence. Many of these have aspects of both outer and inner planes. All of the planes overlap with Eberron in some way, and they influence and are influenced by the material plane. This influence waxes and wanes; scholars often depict the planes as orbiting Eberron, though this purely a metaphor for their shifting influence. When the influence of a plane is especially strong it is said to be coterminous. When its influence is weak, a plane is remote. These states can be important for epic rituals, the creation of eldritch machines or interaction with extraplanar entities. There are also manifest zones: places in the material plane where the barriers are thin and where some aspects of a plane can bleed through. Ghosts may linger in a manifest zone to Dolurrh, while a manifest zone tied to Lamannia might have wild vegetation and enhance druidic magic.
Fernia: The Sea of Fire
Fernia encompasses both the raw elemental force of fire and the idea of fire: flame used as a weapon, as force that holds darkness at bay, as a destructive power and force for change. It is home to all manner of fire elementals and also to celestials and fiends that embody these ideas. Legend holds that a large landmass of ash sits at the center of Fernia on which is found a city known as the City of Brass.
Irian: The Eternal Dawn
A plane of light and hope, Irian is the source of positive energy in Eberron. On Irian, a brilliant white sun hangs in the center of a crystalline sky, bathing the radiant landscape below in shadowless light. Forests of crystalline growths, mountains of pure quartz, rivers of liquid glass, and sunbleached deserts of pure white sand define the landscape of this plane.