Placing Spelljammer and Planescape into Mystara (instead of the other way around)
by Håvard
Over the years there have been many discussions about how to combine the cosmology that originated with BECMI and Mystara with the cosmology that originated with AD&D. This includes concepts like Spelljammer and the AD&D Outer Planes/Great Wheel/World Tree that I am just going to refer to as Planescape here.
In most discussions, the approach has been that we need to find out how Mystara can fit into those other settings. This is the approach that the AD&D Mystara line took. The downside with this is that it usually involves removing some of the more interesting features of Mystara.
Another option that has come up, but that I don't think many have done that much with is going the opposite route? Can we take all the stuff from AD&D and later editions and insert them into Mystara's cosmology. This is what I want to explore here.
One advantage of this approach is that there is more than enough room. Even including all of the fan mapped crystal spheres of Spelljammer, they would together take up a tiny region in Mystara's infinite Prime Plane Universe. We could place it close to the center of the Mystara Galaxy and say that this region functions like how Wildspace is detailed in Spelljammer. Nothing would really have to be changed. There is already canonical information saying this region of Mystara's Universe is heavily magical.
Over to the Outer Planes of the Great Wheel/World Tree AKA Planescape: In Mystara's cosmology we know that the Outer Planes are organized in a very different way, but there is an infinite number of them. Anything we could imagine could be found out there.
I expect a number of potential problems with this model will be brought up, but I am sure that they could all be dealt with. The main advantage of this model is that Mystara gets to retain all of its unique and interesting features and I think that other settings will also be preserved more or less unchanged.