This article was first broadcast in Episode One Hundred Seven on 19th February 2020.
Mikey: Come on, come on, no!
ROSTRO start-up sounds
Mikey: Darn it!
Ryu: I thought you were keeping an eye on him!
Mikey: Yeah, but there was this footnote Lennon wanted me to check out for him about the cosmological disposition of Eberron in the planar landscape and-
Ryu: And now you’re starting to sound like that thing.
ROSTRO: Please state the nature of the mathematical inquiry.
Ryu: Yeah, why did Ostron decide he needed your help with the planes?
ROSTRO: Once cosmological analysis of planes in Dungeons and Dragons moves beyond the elemental planes, the number of areas to be considered increases by a significant number. Due to the number of potential information sources available, Ostron believed it was prudent to avail himself of my proficiency with extra dimensional analysis.
Ryu: You know, I’ve got a little bit of skill with math. I’m pretty sure multiple dimensions in math aren’t the same thing as what we’re talking about here.
ROSTRO: I cannot account for inaccuracies of specificity committed by Ostron when he was designing my operational parameters.
Mikey: So you’re good at knowing things about other dimensions? This should be interesting! What have you got for us?
ROSTRO: Please consult the output crystals for a full report.
Mikey: …which we’ll summarize.
Okay, so in 5th edition, all of the planes beyond the elemental ones are collectively called the “Outer Planes.” Even though physical distance doesn’t really matter when we’re talking about other planes, it’s easier to just think of these as the farthest away from the material plane; getting to any of them requires a significant amount of work, possibly including divine intervention, and the potential danger increases right along with it. The outer planes are like walking into a high quality professional organization; regardless of what they do specifically, even the lowest person in the ranks there is going to be miles better at whatever they’re doing than you are, in most cases.
The most common methods of transportation to any of the planes are through planar portals of significant size and energy. Any portals to the locations mentioned here frequently exhibit noticeable influence on their locations. In some cases the portals are obvious and become the focus of religious or arcane organizations, possibly including buildings dedicated to their presence. Even if concealment is attempted, the energy involved tends to subtly influence the area surrounding an opening. The most obvious example is a portal to the Abyss spreading the corruption exhibited by that plane and increasing the frequency and likelihood of demonic incursion.
Speaking of, the Abyss and the Nine Hells are two of the more well known examples of outer planes. We touched on them when we discussed the Blood War, so we won’t rehash the details here, but suffice it to say neither is a place most people want to spend any length of time.
Examining what could arguably be the complete opposite of those planes, Celestia is the home of many of the more prominent “good” deities in D&D, including Bahamut and Moradin. It is also the home plane for most beings classed as Angels…and you get Holiphaunts there!
Mikey: I don’t think they have them for sale like pet dogs
Ryu: Quiet you.
5th edition is really sparse on details about Celestia so far, but in earlier editions it had seven layers or mountains (depending on the edition) of increasing power and objective good. Reaching the uppermost level theoretically caused creatures to “become one with the plane” and transcend mortal or even deific concerns.
After The Hells and Celestia, Limbo is possibly the next most well known plane, thanks to entries in monster manuals and Mordenkainen’s Tome of Foes. Limbo is officially a completely empty plane, but it can be influenced by strong or disciplined minds, allowing such creatures to literally create something out of nothing. The most famous implementations of this are the Gith, particularly the Githzerai, who create and maintain most of their bases and temples in Limbo. The only native inhabitants of Limbo, at least in 5th edition, are the Slaadi, who try to actively destroy any physical structures in Limbo, or anywhere else for that matter.
Beyond those two planes, many of the other outer planes appear to have taken significant advantage of the fact that many popular myths are not copywritten. The plane of Elysium, for example, is named no differently from the common ancient Roman depiction and bears many similar characteristics; being primarily sunny fields and peaceful areas housing the sun god Pelor. Similarly Pandemonium, a plane composed of dark, windy tunnels and imprisoned beings sent to the plane for punishment, conforms to judeo-christian depictions of a location with the same name. Finally Arcadia is more or less identical to its Greek antecedent, exhibiting a tranquil rural environment of great prosperity and orderly growth, although rather than tranquil human agriculturalists, there are colonies of peaceful subterranean dwarves.
Two other planes are more commonly referred to by other names but borrow a lot from mythology. Ysgard is basically the mythological Norse Asgard. In D&D it has Kord and Olidammara instead of Thor and Loki, but it’s supposedly where heroes go to test their might by climbing mountains and fighting giants and dragons when they’re not drinking with the dwarves that live there. If Odin had copyright lawyers, they’d be having words.
Carceri is only slightly harder to pin down but takes a lot of its nature from the mythological greek Tartarus, where the greek Titans were imprisoned. In D&D the plane is a desolate, harsh wasteland composed of six layers but retains its prison motif because nearly all portals connecting to the plane become one-way after they’re created, only allowing travel into Carceri.
Several other outer planes retained mythological names but acquired purely D&D flavors. Hades, for example, bears some resemblance to the version from Greek mythology, but in 5th edition it’s become a repository for unclaimed souls. Those souls eventually transmute into larvae with humanoid faces and worm bodies. While many other demons, hags, and yugoloths pass through for various reasons, the only other inhabitant of the plane is Abbathor, the god of dwarven greed.
Gehenna is an actual place on Earth, but it has significance as a cursed location in Jewish folklore. In D&D it’s a plane of volcanoes and mountains; literally none of the ground is flat. It’s also significant for being the birth-plane of the yugoloths; any of them that are killed elsewhere reform on Gehenna, which is the only place any of them can be permanently killed.
The case for Acheron as a pilfered label is weaker; while it appears in Greek mythology, it variably refers to a river and an individual rather than a location, and neither bear resemblance to the plane in question. In Dungeons and Dragons, Acheron is one of the more esoteric planes, featuring four enormous metal cubes floating in void. The cubes are inhabited principally by soldiers and warriors who fight each other and, when the opportunity arises, fight other armies on the other cubes on the occasion of a collision. Principal dieties in residence are mostly Gruumsh and Maglubiyet, deities associated with Orc and goblinoid species.
Moving on to planes that are primarily unique to D&D, The Beastlands is a plane of untamed and unrestricted nature, with any beast or plant of natural origin thriving there. Unsurprisingly Ehlonna the goddess of forests is said to spend a lot of time there.
Arborea, despite the name, is not entirely composed of trees, but there are a lot of elves. The easiest analogy to make here is that the plane is a 1960s free love commune taken to the extreme. All the inhabitants are encouraged and able to freely express extreme emotions of all kinds and make no effort to restrict themselves in doing so. In general the inhabitants are said to be good and peaceful, but the extreme emotions sometimes have worrying side-effects.
Mechanus is frankly where I thought ROSTRO was from initially, because it’s entirely mechanical. Cogs, wheels, gears, and just constantly moving machinery make up the entire plane, though what machine all of them are apart of or what the machine is doing are mysteries unknown to anyone. Unsurprisingly this plane’s primary inhabitants are modrons and the entire plane’s deal is keeping everything neutral and orderly.
Finally you have the outlands. The Outlands is an enormous disk or wheel that sits between all of the other planes we just mentioned, with portals to each plane on the edges and settlements reflecting each plane’s nature at the location of the portals. In the middle of the outlands is a very thin, pointed mountain called the spire, at the top of which is the floating city of Sigil. Sigil is an enormous city with more portals to other planes and locations than anywhere else in the multiverse. Think of it like the largest and most complex airport terminal you can imagine. And, like airport terminals, merchants have taken up permanent residence to buy and sell from all of the myriad creatures passing through.
Unfortunately beginning from the summary presented here and attempting further research is fraught with frustration. Currently the only definitive fifth edition source for information on many of these locations is the dungeon master’s guide. Suggestions to refer to previous editions’ information are problematic. Even the small amount of information in the Dungeon Master’s Guide has already contradicted many representations of outer planes as they exist in previous editions. Additionally, where previous editions definitively tied all deities to a location in the planes, that effort has not yet been attempted for fifth edition; the disposition of various deities referenced here represent information garnered from historical references.
However, using previous references as information sources would suffice if the end goal were to establish a basis for an adventure, provided the parties involved are not overly concerned with canonicity or a creative explanation is established to overcome the discrepancies.
Ryu: Wow that took way too long. Did we really need to know about all of those planes?
Mikey: Well, the Research Beholders sometimes wander in here and accidentally end up on other planes, so eventually something is bound to come through the other way and…hang on. You just determined ROSTRO was really good at dealing with other dimensions didn’t you?
Ryu: Oh great. ROSTRO? How many of those dimensional portals were opened by Ostron?
ROSTRO: As you’re aware, I am unable to account for Ostron’s activities while he is conscious.
Ryu: You know that’s not what I’m asking.
Mikey: Wait, did I just see a Modron back there?
Mikey: It was definitely a mechanical leg!
ROSTRO: As you are merely an Audio Alchemist, and not a visual alchemist, your lack of proficiency with visual perception has been historically well documented.
Mikey: … You know I can make you sound like a chipmunk, right?
Ryu: Don’t antagonize it! Last time when Lennon tried to climb on top of it to teach it a lesson, it ended up shocking his hair green when the magical energies–
ROSTRO (interrupting): Multi-phasic quantum-induced concurrencies of layline–
Ryu (interrupting): Ugh, nobody cares! Besides, we need to get over to the scrying pool.
Mikey: Alright, but I’m watching you…
ROSTRO: The probable efficacy of that endeavor does not illicit any particular response.