A D&D Companion supplement should include information on other planes, involving concepts which evolved in the transition from OD&D to AD&D, although diverged in the BECMI line with publication of the D&D Master and Immortals Sets.
The Inner Planes, from the AD&D 1e Deities & Demigods Cyclopedia (1980)
The Ethereal and Astral Planes were introduced in the Eldritch Wizardry supplement, and further defined in "Planes: The Concepts of Spatial, Temporal, and Physical Relationships in D&D" by Gary Gygax, published in The Dragon #8 (July, 1977)*
*see OD&D Cosmology: The Inner Planes of Existence; Notes on the Ethereal Plane; OD&D Cosmology: The Outer Planes; The Astral Plane
AD&D cosmology was described in Appendix 1: The Known Planes of Existence, in Deities & Demigods (the Inner Planes were covered in more detail in articles by Len Lafolka in Dragon #42 (October, 1980) and by Gary Gygax in Dragon #73 (May, 1983)
Information on the Inner Planes is essential, including the Positive and Negative Material Planes (not covered in the D&D Companion Set) as well as the paraelemental planes. Wandering Monster tables for the various planes should also be included.
The Outer Planes were to be covered in the D&D Master Set (1985) which focused instead on introducing a cosmology involving five Spheres of Power. (I would exclude the AD&D outer planes, since they are linked to the AD&D alignment system.)*
*alternately, certain AD&D outer planes could be included as pantheon-based, as opposed to alignment-based outer planes
The Astral and Outer Planes were covered in more detail in the Immortals Set (1986), although the nature of the Astral Plane was revised. I would favour a more OD&D/AD&D based conception of the Astral Plane, and its relationship to dimensions.
Interesting overview. I try to keep cosmology relatively simple. The picture you have included of the AD&D inner planes was a strong inspiration, perhaps the basis, of my previous campaign world's cosmology, explained here: https://kaelaross.blogspot.com/2011/03/cosmology-of-kaelaross.html
ReplyDeleteThe big difference is that the positive and negative energy planes have been replaced by multiple planes of Law and Chaos, inspired by the Elric stories of Michael Moorcock.
That's a very interesting take on it!
DeleteI'd like to include the Positive and Negative Material planes in a B/X cosmology, and linking them to the Law/Chaos axis is a brilliant idea