Is there anything tougher to crack than cosmology? For me the answer is no. Throughout its history, Dungeons and Dragons has handled various planes of existence in all sorts of ways. There is The Great Wheel, Spelljammer, the oft-malign and easily understood Fourth Edition cosmology, World Axis (I got your back, James Wyatt), and so on. What’s a designer to do when in creating one world he realizes now he needs to create a whole multiverse to go with that world?

How I felt when I discovered I had to create worlds beyond Canus to make Exploration Age feel complete.

Personal Likes and Dislikes

My biggest problem with multiverses is that they always seemed overly complicated. I know I’m going to get some flack for saying that, but that’s my personal opinion. Don’t get me wrong, as a DM I love delving into the more complicated minutia between various planes. There are connections and pathways and Demiplanes, Outer Planes, Inner Planes, coterminous planes, coexistent planes, and on and on. Yet for players these complications are dull and slow down gameplay. For the most part they don’t care which plane borders which and how the map of multiverse is drawn.

The thing I love most about the planes are the little details which affect gameplay for the players – the silvery chord tethering a creature back to its body on the Material Plane when traveling through the Astral Plane, or the ability to travel more quickly in the Plane of Shadow are good examples. These concepts are more easily understood by players because they have tangible and immediate effects. They remember the Elemental Plane of Air because they have personal directional gravity in a huge, open, infinite expanse of sky, not because it’s one of the inner planes. These are the details which make planar travel in an RPG interesting.

To be honest I enjoy the variety of planes within The Great Wheel. I want that level of variety in the multiverse of Exploration Age. However I want the simplicity of a Fourth Edition World Axis layout for my players who don’t care that the Elemental Planes are Inner Planes and Celestia is an Outer Plane and all the details which go along with those distinctions.

If your planar map looks like this something has gone wrong.

Sweet, sweet, easy to understand World Axis cosmology.

Cosmology in Exploration Age

So first things, first. Let me be clear here – if you choose to run an Exploration Age campaign you can use any cosmology you want. If you don’t like what I’ve laid out here, that’s totally, 100% fine. Bring The Great Wheel, Fourth Edition’s World Axis cosmology, or any system you want into Exploration Age and play with that. That’s what tabletop RPGs are all about and 95% of Exploration Age’s content deals with the Material Plane anyway.

That being said, here’s what I’d like to present as the default cosmology for Exploration Age is this – certain planes, such as the Ethereal Plane and Plane of Shadow are Coterminous. They overlap completely and in all areas with the Material Plane, like they always have been. This allows for use of spells like shadow walk and blink to be used and to get some of D&D’s most classic planes into the Exploration Age multiverse. Many other planes, not just The Material Plane, have an Ethereal Plane and Plane of Shadow which are coterminous.

Then there are the Reflections – worlds of the same size and with similar natural landforms as the Material Plane. This includes Fourth Edition’s Shadowfell and Feywild and allows for the freaky fun looks-like-our-world-but-totally-isn’t-our-world effect that one gets while adventuring in a plane which reflects our own world.

Other planes are not Conterminous nor Reflections, but they do overlap with The Material Plane in certain places. These areas of overlap are where one might find a standing portal on Canus to a particular plane. One must be careful when using these gateways for sometimes they only work one way. So an adventurer might be able to leave Canus through a portal, but not return, or a monster could wander through a portal in an Overlap Zone and be stuck on the Material Plane.

This overlap also creates Overlap Zones – small areas where the barrier between worlds is thin creating strange environmental effects. It is even possible, in rare places, to have overlap between Overlap Zones. These planes do not just overlap with Canus’ Material Plane. They can overlap with one another (so it is possible to be travel through the Elemental Plane of Fire and encounter an Overlap Zone with The Abyss).

Of course it is possible to travel from one plane to another without being in an Overlap Zone. Spells, rituals, magic objects, and more can take a person from one plane to the next. Overlap zones just make extra-planar travel much easier.

The Astral Plane, which is technically the space between the other planes and the Far Realm are exceptional planes and do not fall into any of the above categories.

In Exploration Age when people die, their souls eventually pass onto the unknown, beyond the multiverse and if there are any gods, they too are beyond the multiverse. This changes things a bit for a few of the classic D&D planes, since the gods and the dead will be spending their time elsewhere.

Let me know what you think about the proposed layout above. For the most part Exploration Age’s planes will be familiar. I’ve already made an entire world with tons of adventure hooks and I didn’t feel the need to remake the wheel when it came to the multiverse (pun intended).


I couldn’t resist adding a few planes of my own design. Take a look at the two below and let me know what you think!


There is a strange Reflection plane where what are considered monsters in Canus rule the land, while what would be considered civilized humanoids live in caves, swamps, and dank, dark ruins. This strange world is ruled by well-dressed ogres, gnolls, and more, who try to keep the humans, elves, and other savage species at bay. Humanoids from the Material Plane who travel to this world are as misunderstood as they are confused.


An infinite region of mountains, forests, tunnels, and swamp makeup Murderfall, the land where everyone wants to kill everyone else. When outsiders enter the plane, they must make a DC 15 Wisdom saving throw or attack any living creature they can sense until it dies. They make a new saving throw after 24 hours to try and end the effect. If they leave Murderfall the effect ends. Creatures native to Murderfall are immune to this effect, but they are all vicious, territorial loners, so it may seem they are under this effect anyway. Essentially everything in this plane is stalking or being stalked.

Overlap Zone All critical hits deal twice the maximum amount of damage.

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  1. joelastowski says:

    You might need to do some work to differentiate between the Shadowfell and the Plane of Shadow, as they will likely share a lot. Still, I like the idea of Coterminous and Reflecting planes.

    I’m a little confused about the dead souls thing, because that would seem to negate many forms of undead on Canus, not to mention making Resurrection spells and Speak With Dead rituals MUCH more time sensitive.

    I think, were I to run a Canus campaign, I might incorporate resurrection and ghosts into that understanding… so that maybe most souls pass on into the unknown, but those with horrible deaths/magic done to them come back as undead, and those with particularly strong destinies/forces of will reincarnate in a future vessel. Maybe it’s just because I really like the Raven Queen (who, let’s be honest, is Neil Gaiman’s Death from the Sandman series, whom I always had a crush on)… she carries the souls to where ever they need to go… whether it’s oblivion, a specific god’s domain, or a new body for reincarnation, and she hates the undead because they represent souls that were taken from her ravens before they could get where they need to be.

    Liked by 1 person

    • For sure violent death and unfinished business and spells and environmental effects and more will create undead. I’m thinking souls still hangout for a bit too so that spells like raise dead and more make sense. But when someone is dead, done deal, not coming back or holding on for raise dead, they move on to unknown. They aren’t hanging out in another plane like they might in some D&D campaigns. It helps keep some of death’s mystery. I should clear that up for sure.


  2. While I agree that the plethora of planes in D&D is a bit excessive, I prefer even simpler schemes, e.g.

    * Planes are abstractions to explain magical effects, not places in their own right. Far locations in the same world are weird enough.

    * Other planes are actually physical locations in the game world, usually in inaccessible places –high mountains, deep in the earth, other planets — where portal travel is the more practical solution.

    * Faerie realms are geographical areas where conventional notions of time, space, and physics become much more fluid.

    * Powerful wizards or godlike beings create “pocket universes” accessible only through a door or tunnel. Or perhaps *ours* is the pocket universe with doors to a greater multiverse.

    * There’s a single “spirit world” with multiple layers, accessible to the living only through dreams or trance states. The layer closest to the material world are where ghosts and minor nature spirits live, while the Deep Spirit World is the abode of beings called gods, demons, and angels depending on one’s particular religion and cult affiliations. (A horror game would use the multi-layered hyperspace of Eldritch Skies or the gibbering madness of D&D’s Far Realm.)

    * All that exists in the multiverse are Worlds and the Void. Travel between Worlds requires esoteric techniques beyond conventional magic or science: void ships, dimensional gates, a specific bloodline, the whim of a Void Horror. Worlds range from alternate histories of the Home World to places where the laws of nature are vastly different and only multiverse-level magic-tech works.

    Ultimately, the goal is to give players an unfamiliar or bizarre environment to adventure in. GMs can explain the differences however they like, or not explain them at all.

    Liked by 2 people

    • These are all pretty great!!!!! Take notes, people!


    • icksy says:

      Nice. There’s some good stuff here. I really like the idea of making ‘planes’ just really out of reach places in the material world. This kinda makes me think of Mount Olympus (in the minds of ancient Greek peasants). And I also like the Worlds/Void idea, which makes me think you might have played some Rogue Trader at some point. 🙂

      Liked by 1 person

  3. icksy says:

    I like the idea of a ‘bizarro world’ plane where everything is reversed. That totally made me imagine these savage cave-man-style humans who hunt in packs and disrupt the civilized upper class ogre society. I might even ‘borrow’ something like this for a future game of my own. 😉

    Liked by 1 person

  4. LumberJack says:

    Boo other planes, BOOOOOOOOO!!!! If you want places like that, make them in your world. If you want abilities like that make spells or items that give said abilities. The other planes stuff always seemed like lazy or bored DM tactics, as a player it was just a second pain in the ass set of rules to remember. An interesting jungle/dungeon/castle/ruins is WAY more enjoyable, than a DM trying to get clever and forcing a deus ex machina story shift to dig out of a plot hole. Unless I’m eating magic mushrooms and chasing white rabbits, or eating Turkish Delight with Aslan, just leave me in the material plane.

    Liked by 1 person

    • Strong feelings and I definitely understand. I more view planes as an extension of the world where you can do some really weird stuff, which I know not everyone is into. But if you want an endless, open, expanse of pure sky where people have personal gravity, that’s pretty dope and planes make sense as a way to do that.


  5. […] This month’s RPG Blog Carnival theme is a great one – “What’s in the hole?” This theme is both oddly specific and wonderfully broad. Metaphorically, the inside of a hole could be any place unknown! I’ve already written a few posts about the blank spots in the world of Exploration Age and how some people in the world want to adventure for profit, power, knowledge, or the sake of discovery itself. All those blank spots in Verda, Glacius, the Poles, The Damned Lands, and The Underdark are really just big holes. Heck even portals are holes to other planes. […]


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