Plane Shift Variant: Co-terminous travel only

[phaedrusxy]

This is based on an idea put forth here: In a nutshell, Plane Shift and similar abilities would only allow you to travel directly from one plane to another plane that is coterminous or coexistent with your starting plane. So if you wanted to travel from the material plane to Mount Celestia, for example, you would have to first Plane Shift to the Astral (or some other plane that is coterminous with both your departure and destination planes), and then Plane Shift again from the Astral to Mount Celestia. More powerful spells like Gate and Wish, and specific abilities like a genie's ability to plane shift to an elemental plane, would override this restriction, when applicable.

Some questions were raised as to how this would work with planes which have multiple layers, like the Abyss, and SirPercival and I decided to start a thread to flesh out the idea a bit more.

I was thinking that the Styx could count as a plane itself, meaning that once you were in one layer of the Abyss, that you could get on or into the Styx, and Plane Shift to any other layer in the Abyss, or indeed any layer of any other lower plane, since the Styx runs through them all. The river that runs through the upper planes whose name I forget could serve the same purpose there.

I think this would serve to make planar travel a bit more interesting, and more dangerous, for those who are just embarking on it. Those with enough power could still just rip a hole between whatever points they wanted via Gate, however. This would also allow the Eberron cosmology to seamlessly mesh with how planar travel in other settings works, as the planes which are unavailable for planar travel in Eberron would be explained to not share any coterminous planes with the prime material plane of Eberron.

Further development of this is welcome, especially questions on how it would work in examples where it might not be obvious. Once we've fleshed it out, I'll convert this post into a "prettier" write-up of it.

[veekie]

Hmm, one possibility is that co-terminous does not necessarily mean the entire plane is co-terminous to the destination. It may always be co-terminous with at least one plane, but you'd need to physically travel on the intermediate plane to reach a point where it syncs with your destination.

So for example, if you want to go to Grazzt's place from the Material.
You start by crossing over to the Astral, and hunting for a Color Pool to the Styx. From there, you cross over to the Styx and navigate along the river to reach the right stretch and punch through.

It does make Plane Shift much weaker as a spell though, as it becomes location dependent.

[sirpercival]

That's an interesting version, veeks, and it just made me think of something: what if cross-planar communication was also screwy?  You can only cast Commune or COP from certain places or planes?  But either way, physical travel cross-plane is only possible in certain places, and via the rivers already.

Anyway, I assume that portals would fall under the category of "specific exceptions"?  Otherwise Sigil would be a big pile of nerf...

Phae, I don't think the Styx/Oceanus thing would work -- if you have to travel the river to Plane Shift, you might as well travel the river and just physically travel and not waste the spell slot, you know?  Though, if you used veekie's idea, maybe you could travel to the river and then shift along the river to any other plane.

[veekie]

Standing portals are always exceptions, presumably the portal's channel runs across all the necessary planes like a phone line. For the most part, the spell generates a planar transition, whether or not there is normally one. So for example, while you could just sail all the way down the Styx and exit into a layer of the Abyss, this means you don't need a specific transfer point or portal, you make your own.

[phaedrusxy]

Hmm, one possibility is that co-terminous does not necessarily mean the entire plane is co-terminous to the destination. It may always be co-terminous with at least one plane, but you'd need to physically travel on the intermediate plane to reach a point where it syncs with your destination.

So for example, if you want to go to Grazzt's place from the Material.
You start by crossing over to the Astral, and hunting for a Color Pool to the Styx. From there, you cross over to the Styx and navigate along the river to reach the right stretch and punch through.

It does make Plane Shift much weaker as a spell though, as it becomes location dependent.

That doesn't sound very different than traveling the planes without the Plane Shift spell, if you can reach the Astral in the first place. I don't really want to nerf it that much. Just a bit off the edges.

Phae, I don't think the Styx/Oceanus thing would work -- if you have to travel the river to Plane Shift, you might as well travel the river and just physically travel and not waste the spell slot, you know?  Though, if you used veekie's idea, maybe you could travel to the river and then shift along the river to any other plane.

Except to go to the 666th layer of the Abyss via boat on the Styx, you'd have to first travel through the first 665 layers... With what I have in mind, you could just get in the Styx at any point in the river (even if you weren't in the Abyss), and then cast Plane Shift and go right to the 666th.

[Amechra]

I like this. I also like the COP idea (that restricts the spell to planes that are coterminous.)

I remember seeing something similar that basically made it so teleporting involved certain fixed location you could set up beforehand in a ritual.

I'll go look around to see if I can find it.

[Tarkisflux]

I remember seeing something similar that basically made it so teleporting involved certain fixed location you could set up beforehand in a ritual.

I'll go look around to see if I can find it.

You may be referring to my Waypoint Style Teleportation, where veekie and I also discussed Plane Shift changes along these lines. Wasn't quite this limited though, just prime -> first layer of outer -> any layer of same outer (though maybe keyed transports could get you closer). The addition of transitive restrictions is an interesting thought though, but I'm not sure if it serves to lengthen exploration and make it more interesting, or if just counts as a spell slot tax on planar travel.