I've been trying to understand the D&D Canonical Multiverse based on the material released in the Dungeon Master's Guide (2024), and it's been quite the journey. Each plane is uniquely complex, and they all interconnect in various ways.
I wanted to compile an "Index" of all these places and how they interact, mainly to help my own understanding. Hopefully, this can be useful to you as well.
- Sigil: The "center" of the Multiverse, filled with portals to everywhere else. - Outlands: A fantastical realm that houses Sigil and Gate-Towns leading to the Outer Planes. - Outer Planes: Diverse realms embodying cosmic ideals and home to extraordinary beings. - Astral Plane: A vast expanse where thoughts and dreams take form. - Ethereal Plane: A dangerous dream realm where mortals shouldn’t dwell. - Elemental Planes: Domains of pure elemental energy such as fire, water, air, and earth. - Elemental Chaos: A turbulent plane of combined raw elemental forces. - Feywild: A magical, vibrant reflection of nature governed by the fey. - Shadowfell: A dark, somber mirror of reality, infused with shadow. - Material Planes: The "standard" places, more akin to classic fantasy worlds.
Sigil
Sigil is a sprawling, dense city where beings from all corners of the Multiverse coexist. Bursting with activity and complexity, it demands a thorough guide to navigate its maze of species, ideologies, and districts.
It's also called "The Center of the Multiverse." While it sits at the heart of The Outlands, I think the name may reflect how every ideology and being converges here.
Known as "The City of Doors," Sigil allows clever seekers to find portals to any destination. Learn more about Portals.
The Lady of Pain has the power to grant or deny entry to anyone in Sigil, regardless of their means of travel. She can paralyze with a mere gaze, transform you into a puddle of meat pie while passing overhead, or banish you to an endlessly shifting, extra-dimensional maze. She certainly has character, that Lady.
Lastly, beware of Razorvine, which grows throughout the city. Knowing about it is essential.
The Outlands
The Outlands is a flat ring with the Spire at its center, and Sigil floating at the top of the Spire. The landscape is extraordinarily diverse and constantly shifting—it’s the ultimate wilderness playground.
Evenly spread along the edge, you’ll find sixteen gate-towns, each with a portal leading to its corresponding Outer Plane.
You can travel from Sigil to the Outlands using one of its many portals. Otherwise, travel to the Outlands typically begins in an Outer Plane via a Gate-Town portal.
Even though it may seem like the Outer Planes exist "around" the Outlands, that’s not actually the case. They exist "somewhere," though no one truly knows their physical location. It’s impossible to travel directly from one Outer Plane to another by simply moving across the plane.
The primary way to enter or exit an Outer Plane is through the Gate-Towns or via a portal. From the Astral Plane you can travel through a Color Pools.
To keep things straightforward, I’ve listed each plane along with its corresponding gate-town and alignment. The order follows The Multiverse Map, arranged in "Clockwork order," starting at 12 o’clock (the top of the ring).
An easy way to categorize the Outer Planes is by alignment, as each Outer Plane corresponds to one of The Nine Alignments.
The Astral Plane is an expansive, silvery void that connects to every other plane of existence in the Multiverse, acting as a vast conduit for interplanar travel. Travelers can reach the Astral Plane from anywhere in the Multiverse and use it as a bridge between distant worlds or other planes.
From the Astral Plane, you can travel to the Outer Planes or the Material Plane by entering Color Pools.
In the Astral Plane, there is no traditional gravity, and navigation is powered by thought—travelers simply think of their destination, and they intuitively sense the direction toward it. Movement speed is also determined by mental acuity, with more intelligent beings moving faster. While in the Astral Plane, creatures do not age, and their bodies require no sustenance.
Despite its emptiness, the Astral Plane hosts a surprising variety of inhabitants and landmarks. Notably, the Astral Plane is home to the Githyanki, mind flayers, and various outposts, ships, and cities established by these and other entities.
One can also find Wildspace systems in the Astral Plane—regions where it overlaps with the Material Plane, containing stars, planets, and unique life forms. Wildspace systems are detailed in Spelljammer: Adventures in Space.
Ethereal Plane
The Ethereal Plane consists of two distinct regions: the Border Ethereal and the Deep Ethereal.
The Border Ethereal envelops the Inner Planes, allowing traversal across them. By entering the Border Ethereal and moving through it, you can return to your original plane at a new location. However, it’s unclear if the Border Ethereal permits direct entry into a different plane you weren’t initially in.
The Deep Ethereal is more challenging to access and less explored. It features colorful, shifting curtains that serve as gateways to other Inner Planes. One notable landmark is the Radiant Citadel, visible from great distances within the Deep Ethereal.
Elemental Planes
The Elemental Planes contain three distinct parts: the Elemental Planes, Para-elemental Planes, and Elemental Chaos.
The Elemental Planes are realms composed of basic elements which form the Material Plane. Some parts can be navigable and livable by fleshy travelers, but going deeper will usually require careful preparation. If you travel far enough, you’ll eventually reach the Elemental Chaos, a realm of chaotic energy and ever-changing landscapes. Traveling these realms requires truly heroic means.
The order follows The Multiverse Map, arranged in "Clockwork order," starting at 12 o’clock (the top of the ring).
Keep in mind that this layout is a comprehensible way to represent the planes. They are not arranged as a ring in space. Their energies can be intertwined and connected in unexpected ways, and other Para-elemental Planes can exist.
The Planes of Elemental Chaos are the ultimate expression of untamed elemental power. This vast, shifting expanse is a place where all elements clash and combine in wild, unpredictable ways. The plane has no consistent shape, structure, or geography; instead, it manifests as a chaotic swirl of firestorms, oceans suspended mid-air, floating mountains, and endless storms of sand and ash.
Travelers in the Elemental Chaos must navigate constantly changing terrain and conditions, where the laws of physics often bow to the whims of elemental forces. Rivers of molten lava might suddenly cool into stone, only to shatter moments later in an explosive geyser of steam.
Within this tumultuous plane, one might discover breathtaking wonders—such as caverns with floating pools of lava encased in glacial walls—or legendary sites like the Great Library of Io, the Dragon God.
Unfortunately, the 2024 Player’s Handbook and Dungeon Master’s Guide offer limited details on the Planes of Elemental Chaos.
For a vivid depiction of how adventurers might experience these planes, consider reading Chapter 2 of Feybound: A Dance of Shadows, which provides an evocative portrayal of this chaotic realm.
Feywild
The Feywild is a realm of heightened emotions and fey creations. It is a vast and ever-changing plane that connects to all Material Planes. In certain locations, this connection is so strong that portals spontaneously form, linking the Feywild and the Material Plane.
One crucial aspect to understand is that time flows differently in the Feywild. The phenomenon, often referred to as Time Warp, can be incredibly unpredictable. It affects locations and groups in varying ways and can even cause certain events to repeat. When traveling to the Feywild and returning to the Material Plane, you may find yourself not only crossing space but also time.
Shadowfell
The Shadowfell is a realm connected to all Material Planes. It serves as a dark, shadowy reflection of the Material Planes, filled with despair and oppressive emotions. When the connection between the Shadowfell and the Material Plane is particularly strong, portals can form, linking the two realms.
Positive/Negative Planes
The Positive Plane and the Negative Plane are sources of raw, primal energy that permeate every other plane in the multiverse. These energies manifest in various forms, shaping fantastical landscapes, fueling paranormal phenomena, empowering restorative and destructive spells, animating the undead, and influencing countless other aspects of existence. For most mortals, direct travel to these planes is fatal.
Material Planes
The Material Planes are a collection of worlds shaped by the energies of the Elemental Planes. Essentially, these are the worlds that have been created and released by Wizards of the Coast and their partners over the years. When your Game Master crafts a setting, it is often a Material Realm.
The sheer number of Material Realms is overwhelming, making it impractical to list them all. In this guide, I will focus on the canonical Material Realms included in the 2024 rule set, and some 2014 ruleset worlds.
I've been trying to understand the D&D Canonical Multiverse based on the material released in the Dungeon Master's Guide (2024), and it's been quite the journey.
I have yet to buy the 2024 version, so I will comment from my understanding of the original 5e DMG.
I’m still unclear on how you initially travel to the Outlands. I assume you first head to Sigil, then locate a portal to the Outlands.
Among the color pools in the Astral, some lead to the Outlands. Plus, most of the gate-towns work in both directions.
An easy way to categorize the Outer Planes is by alignment, as each Outer Plane corresponds to one of The Nine Alignments.
Some are supposed to be intermediaries between alignments. For example, Bytopia is between LG Celestia and NG Elysium, so it is Lawful-ish Good.
The Astral Plane is an expansive, silvery void that connects to every other plane of existence in the Multiverse, acting as a vast conduit for interplanar travel.
Normally the Astral connects the Material and the Outer Planes, while the Ethereal connects the Material and the Inner Planes (plus the Feywild and the Shadowfell).
However, it’s unclear if the Border Ethereal permits direct entry into a different plane you weren’t initially in.
The way I see it, the Border Ethereal is a collective name for multiple ethereal borders, of which there is one for the Material, another for the Feywild, another for the Shadowfell, and one for each of the Inner Planes. Going from one border to another requires traversing the Deep Ethereal, although it is unclear how you go from a border to the Deep. Going from the Deep to a border is done through "curtains" similar to the Astral's color pools, so it might be possible to use such a curtain in the other direction.
Travelers in the Elemental Chaos must navigate constantly changing terrain and conditions, where the laws of physics often bow to the whims of elemental forces.
They made the Elemental Chaos survivable? Nice.
I see no mention of the Positive and Negative planes. Does the 2024 version ignore them? It has never been clearly stated but my take is that, much like the Material exists between the Ethereal and the Astral, the Feywild is found between the Ethereal and the Positive, while the Shadowfell is between the Ethereal and the Negative.
Here is a map I made a while ago. I took some liberties but I think I got the general idea.
Thank you so much for your feedback! I’ve updated the original post to reflect some of your comments. Regarding the Astral Plane, that’s how I interpreted it based on the description and the map included in the 2024 editions. I’ll give it another read to double-check, just to be sure.
So I am not that good at it, but as far as I understand it, there are multiple Universes (Forgotten Realms, Eberron, Dragonlance, Greyhawk, MTG, etc.), each with their own cosmology (FR has the Great Wheel, Eberron the 13 planes, etc.).
With the Spelljammer setting, those Universes are connected by Phlogiston and you can travel from Material Plane to Material Plane.
This is very confusing to me, because the book implies that you travel through space inside the Material Plane and all the planets (Abeir-Toril, Eberron, Krynn) exist in one galaxy. But on each Planet, I have diferent Planes surrounding it? I need some help on that https://19216811.cam/https://1921681001.id/ .
So I am not that good at it, but as far as I understand it, there are multiple Universes (Forgotten Realms, Eberron, Dragonlance, Greyhawk, MTG, etc.), each with their own cosmology (FR has the Great Wheel, Eberron the 13 planes, etc.).
The Great Wheel was originally the cosmology of Greyhawk. It has come to apply to most other D&D campaign settings, such as Forgotten Realms, Dragonlance, Ravenloft and Planescape. Some of these settings are mainly defined by a material world (like Oerth, Toril or Krynn) while others are centered on a non-material location (like the Domains of Dread or the City of Doors).
Then there are settings that still resist the Great Wheel:
Dark Sun is about a world, Athas, where magic has gone haywire, killed most life and severed planar connections. It is possible that it is part of the Great Wheel, but if so it is in a way that makes it very difficult to reach.
Eberron, including the world of the same name, simply has writers and fans who are very insistent on using the Orrery instead of the Great Wheel. 5e describes the Orrery has a mini-cosmology hidden somewhere in the Deep Ethereal, but I haven't seen this idea be particularly well received.
As for the D&D/MTG crossover, it is very recent and no thought seems to have been put on explaining how all these planes might be connected or not.
With the Spelljammer setting, those Universes are connected by Phlogiston and you can travel from Material Plane to Material Plane.
Now that's a tough cookie because, guess what? 5e retconned away the Phlogiston! The new Spelljammer uses the Astral Plane in its place. So now Oerth, its sun and the rest of Greyspace are found in a bubble of vacuum that floats in the psychic haze of the Astral, while Toril, its sun and the rest of Realmspace are in a different bubble of vacuum. There is no longer a solid crystal sphere to separate the vacuum from the Phlogiston. Instead, the vacuum is progressively replaced by the psychic haze as a ship travels away from a material world.
So yeah, it is now unclear if the Material Plane or Planes should still be considered distinct from the Astral Plane. My headcanon is that the bubbles are created by interactions between the Astral and the Ethereal. When you are in the psychic haze, you can't successfully cast the etherealness spell because there is no ethereal border for you to jump to. But as you enter a bubble of vacuum, casting the spell becomes possible as you are now in an area of astral/ethereal overlap. If you then turned around while under the effect of etherealness, you would soon find yourself in the Deep Ethereal, having exited a kind of border bubble. But that's just how I imagine it.
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This post is part of Firemind’s Thief Handbook: 2024+ Edition—a comprehensive guide for the Thief subclass.
I've been trying to understand the D&D Canonical Multiverse based on the material released in the Dungeon Master's Guide (2024), and it's been quite the journey. Each plane is uniquely complex, and they all interconnect in various ways.
I wanted to compile an "Index" of all these places and how they interact, mainly to help my own understanding. Hopefully, this can be useful to you as well.
I’ll be using the PHB - Appendix A: The Multiverse Map as a reference for the rest of this document, so make sure to take a good look at it.
Overview
- Sigil: The "center" of the Multiverse, filled with portals to everywhere else.
- Outlands: A fantastical realm that houses Sigil and Gate-Towns leading to the Outer Planes.
- Outer Planes: Diverse realms embodying cosmic ideals and home to extraordinary beings.
- Astral Plane: A vast expanse where thoughts and dreams take form.
- Ethereal Plane: A dangerous dream realm where mortals shouldn’t dwell.
- Elemental Planes: Domains of pure elemental energy such as fire, water, air, and earth.
- Elemental Chaos: A turbulent plane of combined raw elemental forces.
- Feywild: A magical, vibrant reflection of nature governed by the fey.
- Shadowfell: A dark, somber mirror of reality, infused with shadow.
- Material Planes: The "standard" places, more akin to classic fantasy worlds.
Sigil
Sigil is a sprawling, dense city where beings from all corners of the Multiverse coexist. Bursting with activity and complexity, it demands a thorough guide to navigate its maze of species, ideologies, and districts.
It's also called "The Center of the Multiverse." While it sits at the heart of The Outlands, I think the name may reflect how every ideology and being converges here.
If possible, print Sigil’s map and the Outlands map; they’re invaluable for staying oriented in the chaos.
Explore its districts through the Sigil Gazetteer.
Known as "The City of Doors," Sigil allows clever seekers to find portals to any destination. Learn more about Portals.
The Lady of Pain has the power to grant or deny entry to anyone in Sigil, regardless of their means of travel. She can paralyze with a mere gaze, transform you into a puddle of meat pie while passing overhead, or banish you to an endlessly shifting, extra-dimensional maze. She certainly has character, that Lady.
Lastly, beware of Razorvine, which grows throughout the city. Knowing about it is essential.
The Outlands
The Outlands is a flat ring with the Spire at its center, and Sigil floating at the top of the Spire. The landscape is extraordinarily diverse and constantly shifting—it’s the ultimate wilderness playground.
Evenly spread along the edge, you’ll find sixteen gate-towns, each with a portal leading to its corresponding Outer Plane.
You can travel from Sigil to the Outlands using one of its many portals. Otherwise, travel to the Outlands typically begins in an Outer Plane via a Gate-Town portal.
Sources (from most detailed to least detailed):
- The Outlands - Sigil and the Outlands
- Cosmology - DMG
- The Multiverse - PHB
Outer Planes
Even though it may seem like the Outer Planes exist "around" the Outlands, that’s not actually the case. They exist "somewhere," though no one truly knows their physical location. It’s impossible to travel directly from one Outer Plane to another by simply moving across the plane.
The primary way to enter or exit an Outer Plane is through the Gate-Towns or via a portal. From the Astral Plane you can travel through a Color Pools.
To keep things straightforward, I’ve listed each plane along with its corresponding gate-town and alignment. The order follows The Multiverse Map, arranged in "Clockwork order," starting at 12 o’clock (the top of the ring).
An easy way to categorize the Outer Planes is by alignment, as each Outer Plane corresponds to one of The Nine Alignments.
Astral Plane
The Astral Plane is an expansive, silvery void that connects to every other plane of existence in the Multiverse, acting as a vast conduit for interplanar travel. Travelers can reach the Astral Plane from anywhere in the Multiverse and use it as a bridge between distant worlds or other planes.
From the Astral Plane, you can travel to the Outer Planes or the Material Plane by entering Color Pools.
In the Astral Plane, there is no traditional gravity, and navigation is powered by thought—travelers simply think of their destination, and they intuitively sense the direction toward it. Movement speed is also determined by mental acuity, with more intelligent beings moving faster. While in the Astral Plane, creatures do not age, and their bodies require no sustenance.
Despite its emptiness, the Astral Plane hosts a surprising variety of inhabitants and landmarks. Notably, the Astral Plane is home to the Githyanki, mind flayers, and various outposts, ships, and cities established by these and other entities.
One can also find Wildspace systems in the Astral Plane—regions where it overlaps with the Material Plane, containing stars, planets, and unique life forms. Wildspace systems are detailed in Spelljammer: Adventures in Space.
Ethereal Plane
The Ethereal Plane consists of two distinct regions: the Border Ethereal and the Deep Ethereal.
The Border Ethereal envelops the Inner Planes, allowing traversal across them. By entering the Border Ethereal and moving through it, you can return to your original plane at a new location. However, it’s unclear if the Border Ethereal permits direct entry into a different plane you weren’t initially in.
The Deep Ethereal is more challenging to access and less explored. It features colorful, shifting curtains that serve as gateways to other Inner Planes. One notable landmark is the Radiant Citadel, visible from great distances within the Deep Ethereal.
Elemental Planes
The Elemental Planes contain three distinct parts: the Elemental Planes, Para-elemental Planes, and Elemental Chaos.
The Elemental Planes are realms composed of basic elements which form the Material Plane. Some parts can be navigable and livable by fleshy travelers, but going deeper will usually require careful preparation. If you travel far enough, you’ll eventually reach the Elemental Chaos, a realm of chaotic energy and ever-changing landscapes. Traveling these realms requires truly heroic means.
The order follows The Multiverse Map, arranged in "Clockwork order," starting at 12 o’clock (the top of the ring).
Keep in mind that this layout is a comprehensible way to represent the planes. They are not arranged as a ring in space. Their energies can be intertwined and connected in unexpected ways, and other Para-elemental Planes can exist.
Planes: Water, Ooze, Earth, Magma, Fire, Ash, Air, Ice
Elemental Chaos
The Planes of Elemental Chaos are the ultimate expression of untamed elemental power. This vast, shifting expanse is a place where all elements clash and combine in wild, unpredictable ways. The plane has no consistent shape, structure, or geography; instead, it manifests as a chaotic swirl of firestorms, oceans suspended mid-air, floating mountains, and endless storms of sand and ash.
Travelers in the Elemental Chaos must navigate constantly changing terrain and conditions, where the laws of physics often bow to the whims of elemental forces. Rivers of molten lava might suddenly cool into stone, only to shatter moments later in an explosive geyser of steam.
Within this tumultuous plane, one might discover breathtaking wonders—such as caverns with floating pools of lava encased in glacial walls—or legendary sites like the Great Library of Io, the Dragon God.
Unfortunately, the 2024 Player’s Handbook and Dungeon Master’s Guide offer limited details on the Planes of Elemental Chaos.
For a vivid depiction of how adventurers might experience these planes, consider reading Chapter 2 of Feybound: A Dance of Shadows, which provides an evocative portrayal of this chaotic realm.
Feywild
The Feywild is a realm of heightened emotions and fey creations. It is a vast and ever-changing plane that connects to all Material Planes. In certain locations, this connection is so strong that portals spontaneously form, linking the Feywild and the Material Plane.
One crucial aspect to understand is that time flows differently in the Feywild. The phenomenon, often referred to as Time Warp, can be incredibly unpredictable. It affects locations and groups in varying ways and can even cause certain events to repeat. When traveling to the Feywild and returning to the Material Plane, you may find yourself not only crossing space but also time.
Shadowfell
The Shadowfell is a realm connected to all Material Planes. It serves as a dark, shadowy reflection of the Material Planes, filled with despair and oppressive emotions. When the connection between the Shadowfell and the Material Plane is particularly strong, portals can form, linking the two realms.
Positive/Negative Planes
The Positive Plane and the Negative Plane are sources of raw, primal energy that permeate every other plane in the multiverse. These energies manifest in various forms, shaping fantastical landscapes, fueling paranormal phenomena, empowering restorative and destructive spells, animating the undead, and influencing countless other aspects of existence. For most mortals, direct travel to these planes is fatal.
Material Planes
The Material Planes are a collection of worlds shaped by the energies of the Elemental Planes. Essentially, these are the worlds that have been created and released by Wizards of the Coast and their partners over the years. When your Game Master crafts a setting, it is often a Material Realm.
The sheer number of Material Realms is overwhelming, making it impractical to list them all. In this guide, I will focus on the canonical Material Realms included in the 2024 rule set, and some 2014 ruleset worlds.
2024 Material Planes:
- Greyhawk
2014 Forgotten Realms:
- Sword Coast Adventurers's Guide
- Baldur's Gate Gazetteer
- Waterdeep: Dragon Heist Chapter 9: Volo's Waterdeep Enchiridion
- Candlekeep Mysteries Candlekeep
- Icewind Dale: Rime of the Frostmaiden: Termalaine, Ten Towns
I have yet to buy the 2024 version, so I will comment from my understanding of the original 5e DMG.
Among the color pools in the Astral, some lead to the Outlands. Plus, most of the gate-towns work in both directions.
Some are supposed to be intermediaries between alignments. For example, Bytopia is between LG Celestia and NG Elysium, so it is Lawful-ish Good.
Normally the Astral connects the Material and the Outer Planes, while the Ethereal connects the Material and the Inner Planes (plus the Feywild and the Shadowfell).
The way I see it, the Border Ethereal is a collective name for multiple ethereal borders, of which there is one for the Material, another for the Feywild, another for the Shadowfell, and one for each of the Inner Planes. Going from one border to another requires traversing the Deep Ethereal, although it is unclear how you go from a border to the Deep. Going from the Deep to a border is done through "curtains" similar to the Astral's color pools, so it might be possible to use such a curtain in the other direction.
They made the Elemental Chaos survivable? Nice.
I see no mention of the Positive and Negative planes. Does the 2024 version ignore them? It has never been clearly stated but my take is that, much like the Material exists between the Ethereal and the Astral, the Feywild is found between the Ethereal and the Positive, while the Shadowfell is between the Ethereal and the Negative.
Here is a map I made a while ago. I took some liberties but I think I got the general idea.
Thank you so much for your feedback! I’ve updated the original post to reflect some of your comments. Regarding the Astral Plane, that’s how I interpreted it based on the description and the map included in the 2024 editions. I’ll give it another read to double-check, just to be sure.
So I am not that good at it, but as far as I understand it, there are multiple Universes (Forgotten Realms, Eberron, Dragonlance, Greyhawk, MTG, etc.), each with their own cosmology (FR has the Great Wheel, Eberron the 13 planes, etc.).
With the Spelljammer setting, those Universes are connected by Phlogiston and you can travel from Material Plane to Material Plane.
This is very confusing to me, because the book implies that you travel through space inside the Material Plane and all the planets (Abeir-Toril, Eberron, Krynn) exist in one galaxy. But on each Planet, I have diferent Planes surrounding it? I need some help on that https://19216811.cam/ https://1921681001.id/ .
The Great Wheel was originally the cosmology of Greyhawk. It has come to apply to most other D&D campaign settings, such as Forgotten Realms, Dragonlance, Ravenloft and Planescape. Some of these settings are mainly defined by a material world (like Oerth, Toril or Krynn) while others are centered on a non-material location (like the Domains of Dread or the City of Doors).
Then there are settings that still resist the Great Wheel:
As for the D&D/MTG crossover, it is very recent and no thought seems to have been put on explaining how all these planes might be connected or not.
Now that's a tough cookie because, guess what? 5e retconned away the Phlogiston! The new Spelljammer uses the Astral Plane in its place. So now Oerth, its sun and the rest of Greyspace are found in a bubble of vacuum that floats in the psychic haze of the Astral, while Toril, its sun and the rest of Realmspace are in a different bubble of vacuum. There is no longer a solid crystal sphere to separate the vacuum from the Phlogiston. Instead, the vacuum is progressively replaced by the psychic haze as a ship travels away from a material world.
So yeah, it is now unclear if the Material Plane or Planes should still be considered distinct from the Astral Plane. My headcanon is that the bubbles are created by interactions between the Astral and the Ethereal. When you are in the psychic haze, you can't successfully cast the etherealness spell because there is no ethereal border for you to jump to. But as you enter a bubble of vacuum, casting the spell becomes possible as you are now in an area of astral/ethereal overlap. If you then turned around while under the effect of etherealness, you would soon find yourself in the Deep Ethereal, having exited a kind of border bubble. But that's just how I imagine it.