Before stepping through any door, a body'd better have a quick lesson in cosmology - how else is a basher going to know where and what things are? First, it's important to know just what a plane is. To the serious philosopher types, a plane's a world, or a collection of worlds, that operates according to its own particular laws, including those affecting magic, gravity, and even the mortals of the place. On some of these planes, the laws of "up" and "down" aren't the same; on others, evocation magic yields different results; and elsewhere, behaving even slightly out of line with the powers of the place makes for grim results.
Planes are either immense and infinite, in which case they're just called planes, or they're limited by definite borders and are called demiplanes. The exact number of planes is unknown and probably infinite, and planar travellers know of only three major categories: the Prime Material Plane, the Inner Planes, and the Outer Planes. Still, those three have more than enough space for a flaming large number of different planes.
To get around in the planar multiverse, there are three basic rules to remember. These truths pretty well describe the structure of the multiverse, so learn them well!
|The Center of the Multiverse||The Unity of the Rings||The Rule of Threes|
The Grand Design
Okay, enough philosophy. The next question is, "How does the whole multiverse fit together?" Well, that depends on who gets asked. A Bleaker will say there ain't no scheme, while a Godsman will go on about innate celestial glory and the like. None of them will answer the question straight. Maybe the best thing to do is to get a hold of the Guvners and ask them. (Fact is, their answer's no better than anyone else's, but they like to put things into nicely defined categories, and at least that'll give a clear picture.) Their answer would go something like this:
There's three (remember the Rule of Threes?) basic divisions of the multiverse. Although they're all connected to each other in a variety of ways, it's easiest to picture each as separate from the others.
|The Prime Material Plane||The Inner Planes||The Outer Planes|
Travelling the Planes
There's more out there than just the Inner, Outer, and Transitive Planes, though. They aren't all butted up against each other, nice and tight. There's roads and rivers between them, loosely linking the multiverse together. After all, how's a body to get around without paths? Fact is, there's three ways to move around the planes. All three methods of travel have their uses, because not all three ways are always there.
The Ethereal Plane
The Ethereal is the conduit between the Prime Material Plane and the Inner Planes. Every place on the Prime is touched by the Ethereal's vapors, and every point of the Inner Planes is part of the ghostly web, too. Just knowing it's there won't do much good, though - it takes power to break the wall between the planes. Spells and magical items can do it, if a berk's got them. Then again, vortices - rare places where the Elemental Planes bleed right into the Prime Material - can short-cut the whole journey, carrying a sod straight from the Prime to one of the Inner Planes, or maybe even back again. (A volcano's a typical spot to look for a vortex to the plane of Fire, for instance.)
Some folks say the Ethereal Plane's a big, misty place with nothing in it. That's one way to tell the liars, because the Ethereal's really a busy place. Along its edges (it's infinite and touches everything, but it still has edges, so go figure), a fellow can see into neighboring planes. Move off the edge of your plane, into the Deep Ethereal, and it's like an ocean. A body can swim for leagues without touching anything and then, all of a sudden like, there's an island floating in the mist. These are demiplanes, little pocket worlds with rules and realities all their own. Sometimes Sigil spits one of these out at the command of the Lady of Pain - special prisons called Mazes, for her would-be conquerors - and some demiplanes are "grown" by Wizards. Most of them are safe enough, but there's rumors of one that's a place of absolute terror - few folks ever come back from that one.
The Astral Plane
The Astral is what's needed to get from the Prime Material to the Outer Planes. On the Prime it touches every place, just like the Ethereal Plane, yet those two planes - Astral and Ethereal - never meet. The Astral Plane also connects to each of the Outer Planes, provided a body knows where to find the door.
Some folks say traveling the Astral Plane's the hardest of all. Most of these folks are primes, who have to deal with silver cords that tether them to their bodies back on the Prime. Planars don't have that problem, of course, but it still isn't that easy to cross the boundary into the Astral realm. The best way's by the astral spell, granted by the Powers to their special servants. Wizards favor magical devices. The most direct routes are through conduits and color pools, which can sweep a body straight from the Prime Material to any of the Outer Planes.
Although it looks empty, the Astral Plane's a pretty busy place. Travelers there better be ready to deal with the Githyanki, because the silvery void's their home. Huge fortresses filled with their kind drift through the silver stream, and Githyanki ships have been sighted sailing the Astral Plane. The Githyanki aren't alone, either. There's other stuff bigger and meaner than them, like astral dreadnoughts, astral whales, and islands formed from the decaying corpses of ancient powers. Most travelers treat this plane as a good place to leave quickly.
With Sigil at the center, The Outlands are the last pathway to the Outer Planes. Sure The Outlands are one of the Outer Planes, but this one's different from the others. It's not part of the ring - it's the center of the ring. Journey across The Outlands (or the Land, as some call it) and eventually a body gets elsewhere - not just elsewhere on the plane, but into another plane entirely. The farther a body goes toward a plane on the ring, the more the Land looks like that plane, until at last he (or she, or it) comes to a gate between here and there.
Out on the Land the gates are fixed. If a body knows the way around, then he can always find the door. A lot of portals have little towns next to them, where traders and mercenaries who've got business with denizens beyond the gates meet - towns like Glorium (near Ysgard), Plague-Mort (near the Abyss), and Ribcage (near Baator). Some of them are actually quiet and safe little burgs, while others are almost as horrible as the planes they watch.