Spelljammer and Planar Travel

 In a series of videos released on the D&D Youtube channel, Chris Perkins (lead narrative designer for D&D) outlined a bit of the way that Spelljammer (coming out in one month minus one day!) in 5th Edition will look.

Because there hasn't been a sourcebook for Spelljammer in about 30 years, for the most part we've been operating on some very old-school lore.

So, here's the caveat to the following paragraph: this is all old stuff that is being changed.

In the old Spelljammer lore, each region of Wildspace around an established setting (or other regions) such as Realmspace, Krynnspace, Greyspace, etc., was encapsulated by a "crystal sphere," which was an impenetrable barrier that only certain types of magic could pass through - including a spelljammer ship (equipped with a spelljamming helm). The various crystal spheres were then afloat in something called the Phlogiston - an odd soup of extremely volatile fluid that had various odd effects, including barring any divine magic from taking place within it.

The spheres and the phlogiston, in this old lore, essentially made up the Prime Material Plane.

But things are changing:

The phlogiston, conceptually, appears to be completely gone. As are the crystal spheres.

Instead, regions of Wildspace exist now as kind of bubbles of reality that then lead on to the Astral Sea.

Spelljamming in 5th Edition will mean traversing Wildspace, which is a fantastical version of outer space that is dense with colorful nebulae, space-based life forms, and settled worlds, and then, if you go far enough, you'll pass through a threshold into the Astral Sea, where things get hazy and silvery, and time doesn't really pass except in a sort of subjective way. Here, dead gods and crystalline structures float freely. Getting to another Wildspace region simply requires that you navigate the Astral Sea and plunge back into it.

The implications here are actually pretty enormous.

First off, it turns the Prime Material Plane from being one continuous region of spacetime, but into these little islands or bubbles of worlds afloat in the Astral Sea.

Second, it means that interplanar travel, at least when going from the Prime Material to the Astral Plane, is simply a matter of going far enough in any given direction. The Astral Plane, after all, has portals that float within it to all the Outer Planes, and that means that you could, in theory, travel from Toril (The Forgotten Realms) to Elysium by simply getting on your spelljamming vessel and finding the right color pool in the Astral Plane.

Cosmologically, prior to these changes, the Astral Plane linked the Outer Planes, and I believe also connected with the Ethereal Plane, meaning that if you didn't have the planar equivalent of teleportation (basically the Plane Shift spell) you'd need to find a way to get into the Border Ethereal, then the Deep Ethereal, then the Astral, and then to your outer plane of choice if you wanted to get there.

I'll also note that the description of the Radiant Citadel is curious - it exists in the Deep Ethereal, but also sounds comparable to some of the things described as being afloat in the Astral Sea.

Now, to be fair, the Astral Sea is said to be one part of the Astral Plane - perhaps the "Sea" and the parts that allow access to the Outer Planes are not so easily traversed.

I'm very curious to see how the Inner Planes interact with the Astral - the Feywild and Shadowfell are the planes I tend to think of as being closest to the Prime Material, so does that mean you can travel from them to the Astral Sea as well?

I don't know to what extent the Spelljammer books will get into this nitty-gritty of planar mechanics. I've felt for a while now that I'd love to see a 5th Edition Manual of the Planes, both to add detail to the various Outer Planes that don't get as much exposure as the Nine Hells, but also perhaps to clarify some of these nuances.

I'm eager to get the Spelljammer box set in my hands. I'm mildly skeptical of how much detail we're going to get given how short each of its component books are (if all are 64 pages, that means the whole thing is only 192) but I'd love to see some discussion on what sort of planar interactions can happen with the Astral Sea.