Codex notes

[stevenehrbar]

1) The Material Plane

The Material Plane has three "echo planes" — the Ethereal, Shadow, and Faerie. 

• Shadow works as in SRD
• Ethereal works as in SRD, plus travel along the fourth spatial dimension will drop you in the Ylem (q.v.).
• Faerie is a reflection of the Material Plane that is inhabited by fey creatures, and has the flowing time trait.

2) The Ylem

Stole the word from modern physics, which apparently dragged it out of an old dictionary in the 1940s.  Refers to "primordial substance from which all matter is formed".  That is, this is the primordial 'chaos' from which the multiverse was fashioned.  It touches the Ethereal and Empyrean (q.v.), and is generally considered to "contain" the Inner Planes.  Magic is not required to move from the Ethereal or Empyrean to the Ylem or from the Ylem to the Inner Planes; the same types of magic used on the Material to enter the Ethereal allow passage the other direction.  Contains a number of demiplanes . . . some under the control of beings that want to return the whole multiverse to ylem.

3) The Inner Planes

Positive Energy, Negative Energy, and Elemental Air, Earth, Fire, and Water from the SRD.  Para-elemental planes of Fog, Smoke, Wood (Earth-Air), Lava, Mud, and Steam (Fire-Water).  Quasi-Elemental Planes of Lightning, Vacuum, Metal, Sand, Light, Cold, Acid, and Salt.

Inner Planes are mostly vast stretches of their given element.  Some areas, however, seem to echo the Material Plane.  Here you find, say, gravity, a ground of solid fire, with lakes of liquid fire, and an atmosphere of gaseous fire, inhabited by what look like four-eyed six-legged badgers made of solid, liquid, and gaseous fire.  Since the planes are infinite, these echo regions can be really, really big.  As big as the GM wishes them to be.  Big enough that people can mistakenly believe the entire plane is like that, because they traveled for years in such a zone without reaching the edges.  Infinity has lots of room for entire galaxies.

4) The Empyrean

Also known as the Firmament, the Outer Planes are "within" the Empyrean.  Godlings who can't stand to have a realm on one of the seventeen infinite Outer Planes create their own demiplanes here.  The Empyrean has "natural" portals to and from Outer Planes, and to the Ylem.

5) The Outer Planes

LE Nine Hells, LE/NE Gehenna, NE Hades, NE/CE Tarterus, CE Abyss, CE/CN Cocytus, CN Limbo, CN/CG Mag Mell, CG Olympus, CG/NG Shangri-La. NG Elysium, NG/LG Paradise, LG Heaven, LG/LN Aaru, LN Nibiru, LN/LE Acheron, and N Sheol. 

Bit about the Outer Planes being infinite in at least three spatial dimensions.  Which means anything you read elsewhere about the geography of a plane being entirely clockwork wheels might be absolutely true . . . for a volume of space five hundred trillion parsecs in diameter. That doesn't mean that different geography doesn't exist on the plane.  It's infinite.  Certainly, some constants exist which define the plane; Inner Planes tend to be uniform in their substance; Outer Planes tend to be uniform in their alignment.  But if the greater god Mastrack, the Invincible and Implacable Overlord, wants a galaxy-sized region of rolling hills bathed in an eternal sunrise?  Hey, that's what his part of the Nine Hells looks like.  I'm not going to tell him he's wrong.

Suggestion on the afterlife:  When an intelligent being other than an outsider or an elemental dies, its soul generally goes to the plane which matched its alignment.  There, it will usually dwell a while before reincarnating (though other fates can occur).  Especially dedicated followers of a specific god instead go directly to that god's realm in the Outer Planes regardless of alignment, where they are then disposed of as that deity sees fit.  Souls on the Material Plane reach the Outer Planes visa the Ethereal-Ylem-Empyrean.  If their attachment to the Material is strong enough, they manage to halt this travel process on either the Material (becoming a corporeal undead) or Ethereal (ghosts being the prime example of the latter).

(Why the terms Inner and Outer?  Because, from the Material, it's easy to get to the Ethereal, which then gets you to the Ylem, which then gets you to the Empyrean.  So, the Inner Planes seem to a being on the Material plane to be closer, and the Outer father away.  Map of a Material-centric cosmos shown with the Ylem as a ring around the Material and the Empyrean as a ring around the Ylem.)

6) The Astral

As per the SRD, the Astral touches all other planes in the multiverse.  Discovery of the Astral upended the whole Inner/Outer logic, but the nomenclature is too useful to ditch. 

7) Other planes

The "Elemental" Plane of Time, the "Manifest" Plane of Psionics, and the Plane of Dreams are poorly-attested; among the few things known about them is that they are deadly. 

(On the Plane of Dreams, the city of Celephaïs is known to be safe from the ravages of dreamstuff; elsewhere, reality is completely fluid and completely outside the visitor's control.  Best to visit in your sleep; visiting physically is a good way to get killed by an army of tarrasques in your underwear.)

Alternate Material planes can exist alongside the campaign material, or they might be off in their own parallel multiverses, which may or may not be accessible by magic/via the Plane of Shadow.  Because it ins't enough to have a multiverse of at least 57 infinite universes and some impossible number of demiplanes; there might be an infinite number of multiverses.