Moving between different D&D universes

Question

I have a group of mid-high level players. As part of some D&D shenanigans, I wanted to have them plop into Athas (Dark Sun) as a surprise joke. But knowing them, sadistic as they are, they might want to return.

How would it be possible for them to move between universes or return to their home universe? I know I can just DM it any way I want, but I wanted to ask you all if that's possible on their behalf. For instance, a would using a wish spell, a gate, or the Plane Shift work (using game mechanics)?

Would Athas be considered a plane?

Answer 1

Within the default D&D cosmology, Athas is not a different plane, but is in another crystal sphere in the prime material plane. You can have a look at the following answer for the nuances between those concepts: Defining Realms, Worlds, Kingdoms, Planes, Dimensions and the Multiverse

While as a DM you might allow other ways of travel like planeshifting, the 'most common' means of travel between two crystal spheres is through spelljamming. This involves using flying ships to travel to the edge of space, enter the phlogiston and enter the space of the alternate crystal sphere.

However, it is worth noting that in the past editions it had been established that the Athas crystal sphere is sealed, you cannot travel to it through spelljamming. Actually it was way difficult to travel to Athas in any other means either. The portals to Athas were very rare. Please see this question: Entering and exiting Athas and this: Transporting players from Faerun to Athas (Dark Sun)

Finally, I should add that as the DM, you are of course not constrained by these 'official' means. However before introducing "easy" ways of travel, please give a good amount of attention to the consequences. For example the lack of metals on Athas might make the platemail armor of the party's fighter a "center of attraction" in a world with half-giant gladiators.

Answer 2

While no official books discuss traveling between different Material Planes, Mike Mearls (a designer for 5e) has spoken about it in a youtube video by D&D Beyond.

Then within the material plane, you have crystal spheres; each of which hosts one or more worlds, which ... typically the worlds in the crystal spheres ... when you look from sphere to sphere; they're very similar; they're typically... at least one of them is earthlike ... but they might have differences in how magic works, some worlds might have more magic, others less, which gods have influence, and which creatures you might find there, but they're all generally earthlike

What it boils down to is the construction of a vessel capable of traversing the stuff between "crystal spheres" (regions that house different Material Planes) which is called "phlogiston". There are no rules in 5e for this yet, but you can get some insight by reading the Spelljammer campaign setting for AD&D 2e

Answer 3

The 2E Dark Sun adventure "Black Spine" has a way to/from Athas.

In the gith mines is the Nightmare Gate which allows travel to the Astral plane. The gate is destroyed in the adventure, but still stands as an in print example of planar travel to/from Athas.

Answer 4

By allowing your players to visit a world, you are making it part of your universe.

Any world can be freely visited by players, provided that:

1. You acknowledge it as existing in your universe.
2. Players have a means of getting to it.

By moving your PCs to Athas you are effectively taking care of criteria #1. They couldn't have visited it if it didn't exist.

Now that your players know it's a real place that they can visit they can just go there directly using a spell such as Plane Shift. If none of them can cast this spell they might be able to enlist the help of a high level spellcaster who can cast it for them.

Some other means of travel between planes detailed in question What are all the ways a player can get to the Astral Plane? might also be usable here.

This being said you are the DM and can rule that a plane-eating monster devoured Athas or that a jealous deity blocks access to it.

Answer 5

If you don't want there to be a way back to Athas, then there is simply no way for the characters to get back the Athas.

In previous editions, Spelljammer and Planescape went into detail on how travel was possible between worlds. It was almost trivial to travel between Faerun, Krynn, or Oerth.

On the other hand, other settings were deliberately described as difficult or impossible to reach. Athas and the Ravenloft demi-planes were of this nature.

As a suggestion on how to set-up your one-time trip to Athas:

Have the characters come across an ancient portal. Perhaps the landscape surrounding it is a slowly growing area of sickly and dying plants. This area could be starting to encroach on fertile croplands, or perhaps the "worthless" land has been granted to a character and he wishes to break the land's "curse".

When the characters cross to Athas, the portal goes dead. A portion of their adventures in Athas will be a quest to re-activate the portal.

Once the Athas episode is done, the characters activate the portal and cross back to their world. Whenever one of the characters enters the portal, all the other characters are also pulled through. Once back in their world, the portal once again goes dead, this time also crumbling to dust.

With the portal gone, the land is no longer having its life drained away, and it can recover its fertility. Also, with the portal gone, there is no other way to travel to Athas.