Let’s face it, the Dungeons & Dragons cosmology has never really made sense. Each edition brings us another valiant effort to make something coherent out of several decades of uncoordinated shared universe writing. How has the Fourth Edition Manual of the Planes changed things, and how will it affect the market value of your summer home in Gehenna?
The most obvious change is that the Great Wheel is gone. The radial configuration of Inner and Outer planes presented an interesting way of perceiving other dimensions, but wasn’t especially easy to grasp. The best thing about the Great Wheel was probably the graphic that depicted it as a series of overlapping clockwork lenses. Instead, we have the Mortal World and a few parallel realms sandwiched between the predominantly fiery Elemental Chaos below and the decidedly celestial Astral Sea above. Neither of those areas are inherently good or evil, but it’s hard to dismiss the impression that they are “Heaven” and “Hell” due to the way they are depicted. Interesting choice.
So the Material Plane is now called the Mortal World, which could be any of the D&D campaign worlds or your homebrew world. The Transitive Planes (Ethereal, Shadow, Astral) are basically gone. In their place are two Parallel Planes that play a far greater role in the day-to-day activities of the Mortal World than the old Transitives did. The Shadowfell and the Feywild overlap the Mortal World directly. A location in the Mortal World exists in both Parallel Planes, but it may appear quite different. Feywild locations tend to be subsumed by wilderness, while the Shadowfell presents a gloomier, decrepit version. Elves and Eladrin are ostensibly from the Feywild, while undead and Bauhaus fans draw their power from the Shadowfell.
The Inner Planes of old are now part of the Elemental Chaos. There is no longer a specific Plane of Fire or Air or whatever, and the negative and positive energy plains are gone completely. Instead, the Elemental Chaos is dotted with Elemental Realms, formed out of raw elemental substance by powerful beings (sometimes deities). A given realm may appear similar to a “pure” elemental plane, but it will be bent to the whims of the creator, and can combine multiple elements. Notable Elemental Realms include the City of Brass and the Abyss. In fact, many of the old Outer Planes have found a new home as realms within the Elemental Chaos or the Astral Sea.
The Astral Sea is similar to the Elemental Chaos, except it’s more…astral. Instead of realms, it has dominions, and most dominions are created by deities. Theist characters who believe in specific locations for Heaven or Hell may actually be referring to dominions – don’t be deceived into thinking the Astral Sea is “celestial” or good. You’ll find the Nine Hells and Pandemonium floating around out there, along with Celestia and other happier places.
What about the Demiplanes, those weird little pockets that never seemed to fit anywhere? They still don’t fit, but they’re still there. Sigil, the City of Doors, makes an appearance as a Demiplane, and though it isn’t mentioned, one can easily imagine various Ravenloft realms floating around in their mist-enshrouded pockets.
That leaves us with the Anomalous Planes, those dimensions so alien and bizarre that mortal minds can barely comprehend their existence, much less understand or visit them. The best Anomalous Plane is the Lovecraftian Far Realm, home to freaky chaotic shambling oozing horrors with tentacles galore. There’s also a Plane of Dreams and a plane that exists on the other side of mirrors, which actually don’t seem all that bizarre to me.
As for other Mortal Worlds, they’re out there, just really far away. So if you’re playing in the Forgotten Realms, you can go visit the Faerûn version of Celestia. If you start swimming through the Astral Sea, after a long, long, long, long, long, long, long, long journey, you’d eventually reach the Oerth version of Celestia. Or, as the book suggests, just make a portal.
There you have it, fellow planar travelers. D&D cosmology is still a confusing mess, but hopefully now you can see how it’s a bit different from the last edition’s confusing mess.