First I'm going to give the essential information for those running 5th edition D&D games. Then I'm going to go back over the older editions and pull out useful information that can enhance a visit there.
There's one book that has pretty everything you will ever need to know about the ethereal plane:
Guide to the Ethereal Plane by Bruce Cordell
I have long found the ethereal plane to be extremely confusing. It seemed so similar to the Astral Plane. I would actually avoid using it because I just didn't know anything about it.
Let's go over the 5th edition information first, then we'll dig back and see what other cool stuff is out there.
The Essential Information
Here's the basic stuff you should know about the Ethereal Plane:
- Overlap: The Ethereal Plane overlaps the world. You can see and hear the world from the Ethereal.
- Safety: When you're in the ethereal, most people in the world can't see or affect you with a few exceptions.
- Walk Through Walls: If you have the ability to go ethereal, you can utilize it to walk through walls, spy on someone or escape a deadly battle.
- Two Halves: The Ethereal Plane is broken into two sections, The Border Ethereal and the Deep Ethereal.
- Portals: The Ethereal is full of floating "curtains" that are portals to other planes
- Demiplanes: The Ethereal is where demiplanes are made. You can even learn spells to create or destroy demiplanes.
"The Ethereal Plane is a misty, fog-bound dimension that is sometimes described as a great ocean. Its shores, called the Border Ethereal, overlap the Material Plane and the Inner Planes, so that every location on those planes has a corresponding location on the Ethereal Plane. Certain creatures can see into the Border Ethereal, and the see invisibility and true seeing spell grant that ability. Some magical effects also extend from the Material Plane into the Border Ethereal, particularly effects that use force energy such as forcecage and wall of force. The depths of the plane, the Deep Ethereal, are a region of swirling mists and colorful fogs."
The Ethereal Plane is further described on page 48 of the Dungeon Master's Guide. We learn:
- Overlap: The Ethereal Plane overlaps both the material plane and the inner planes. Every location on those planes has a corresponding location on the Ethereal Plane.
- Flying: The laws of gravity don't apply. A creature can move any direction, even up or down.
- Being Ethereal: Creatures in the Ethereal can't attack creatures on the overlapping plane, nor affect objects or be heard.
- Ether Cyclone: Twisting vortexes in the Ethereal that can hurl travelers into a random plane.
- The Border Ethereal: Visibility is limited to 60 feet. You can see 30 feet into whatever plane it overlaps.
- The Deep Ethereal: Travel through the Deep Ethereal takes d10x10 hours no matter where one is headed. Visibility is 30 feet. There are portals scattered throughout this area leading to the Shadowfell, the plane of fire, and other places.
The Etherealness Spell: This 7th-level spell is on page 238 of the Player's Handbook. It allows the caster to travel into the Border Ethereal for up to 8 hours.
Other spells that interact with the Ethereal Plane:
- Plane Shift: Allows casters to go to the Border Ethereal or the Deep Ethereal.
- Blink: On a roll of 11 or higher, the caster appears in the Ethereal Plane.
- Forbiddance: It blocks out creatures from the Ethereal plane.
- Leomund's Secret Chest: The chest and its contents are actually floating in the ethereal!
- Mordenkainen's Faithful Hound: It can see into the Ethereal.
- See Invisibility: The caster can see into the Ethereal Plane. Ethereal creatures and objects appear ghostly and translucent.
- True Seeing: The caster can see into the ethereal plane up to 120 feet.
- Wall of Force: The wall extends into the Ethereal.
Magic Items: There are two items that deal with the ethereal:
- Oil of Etherealness (DMG page 183): You can use this to cover one medium-sized person with the oil, which causes them to gain the effects of the etherealness spell for one hour.
- Plate Armor of Etherealness (DMG page 185): Once per day you can speak a command word and gain etherealness for 10 minutes. This armor is legendary - extraordinarily rare.
- Ghost: Ghosts can see into the Ethereal, and they can shift to and from the plane.
- Kuo Toa: These fish-men can actually see 30 feet into the Ethereal.
- Night Hag: They can visit a sleeping person ethereally and intrude on their dreams. If the victim dies in their sleep, she can claim their corrupted soul in her soul bag. Hags can use their heartstones to travel to and from the Ethereal Plane.
- Nightmare: These evil horses can take three willing creatures within 5 feet to and from the Ethereal.
- Phase Spider: They can shift into the ethereal, using the ability to sort of "teleport" around the battlefield.
- Succubus: They can travel to and from the Ethereal. They like to visit people in the ethereal, whispering forbidden pleasures. This makes the victim more susceptible to temptation in life.
Becoming a Spirit in the Border Ethereal
Check out page 116 in Icewind Dale: Rime of the Frostmaiden. If a character dies in the Black Cabin, they become a spirit in the Border Ethereal.
"If a character dies in the cabin and its spirit manifests in the Border Ethereal, the player can choose the form the spirit takes. It might look like a spectral image of the dead character, or it might be something bizarre like a ghostly crow or a blob of ectoplasmic energy."
- The spirit is not a creature.
- Can't be harmed or turned.
- Can't make attack rolls/saving throws/have conditions applied to it.
- Can't cast spells/attune to magic items.
- Creatures on the Material Plane can't see the spirit without an ability/magic that lets them see into the Border Ethereal.
The spirit can do the following and nothing else:
- Fly speed of 30 feet, can hover.
- Pass through solid surfaces visible on the Material Plane.
- Can make ability checks based on DEX, INT, WIS, and CHA,
- As an action, can make a CHA check DC 10 to attempt to exert up to 5 pounds of force on a creature or object no more than 5 feet away from it in the Material Plane.
- Can see other spirits in the Border Ethereal and speak to them. The spirit knows the languages it knew in life.
|A Waystation in the Ethereal Plane|
There's a note that "an enterprising spell caster can utilize the Leomund's secret chest spell as a method of travel..." Other fun facts:
- Protection: Buildings can be treated with an alchemic mixture containing gorgon's blood that can be mixed into the mortar of a building. This prevents ethereal and astral creatures from passing through.
- You Can't Make People Explode: A traveler cannot materialize partially inside the body of an enemy! All living beings, including plants, have an aura that prevents ethereal travelers from passing through them.
- Time is Slower: Time passes ten times slower in the Ethereal Plane. A ghost's attack would drain only d4 years off of your life in the Ethereal.
- Eat Less: You still get hungry, but less so. You only need to eat every 10 days.
Stuff You Run Into: There's all sorts of weird stuff in the ethereal:
- Supply caches containing food and water for 100 days, meant for long trips through the ethereal.
- Waystations: Places like taverns or guardposts for nearby curtains
- Beings turned into ethereal stone (the most common item found in the border ethereal)
- The Demi-Plane of Shadow
- The Demi-Plane of Time: Those who enter leave much older or younger.
- The Demi-Plane of ElectroMagnetism: A dying realm being devoured by the quasi-elemental plane of lightning.
- The Demi-Plane of Imprisonment: This is only a rumored location, a place where beings of great evil are trapped.
A Guide to the Ethereal Plane
- It connects most worlds, aka the Forgotten Realms, Oerth, etc. Krynn and Dark Sun aren't reachable.
- The Ethereal connects to the Inner Planes (the elemental planes). It doesn't connect to the outer planes or the astral plane.
- Nothing sits in relation to anything else. Relative distance lies only in your perception.
The Wall of Color: This is a shimmering wall of ethereal mist that is seemingly infinite. It contains portals to every elemental plane, the prime material plane and a pile of demiplanes.
Chronolily: These giant flowers let you see into the past, present or future. Its petals form a bowl that contains a golden nectar. Images shift in them at random every 30 seconds. Certain wizards have figured out how to control what it shows by plucking petals in a certain sequence.
Ether Gap: A rip in the ethereal plane that is like a black hole. If you get sucked inside, you are lost to the multiverse. Not even a wish can bring you back.
Protomatter: Blobs of stuff that make up demiplanes. There's 3 types:
- Ephemeral: 99% of the time it turns back into ethereal mist within a few seconds. It feels like a clump of fluffy snowflakes.
- Quintessential: This stuff feels like a cork. The blobs are up to 1,000 feet long. You can chip them up and make weapons or construction materials to make buildings but it only lasts for d100 hours before becoming mist.
- Stable: It feels like metal sheathed in a thin layer of leather. This eventually becomes a demiplane.
- (lvl 5) Stabilize Ether: It stabilizes protomatter, allowing you to use it to make stuff.
- (lvl 6) Dissipate: The victim boils away and merges with the mist. Only a wish spell can bring them back to life. Yikes.
- (lvl 8) Demiplane Seed: This creates a demiplane in the Deep Ethereal. The demiplane grows one foot in radius every day to a max of 10 feet per level of the caster. The caster can create whatever environment they wish.
- (lvl 9) Demiplane Decay: This spell actually destroys demiplanes.
There's a chart that you can use to roll up a random demiplane. Let's make one:
To get to my demiplane, you must pass through an olive curtain. The demiplane is 3 miles in diameter and contains a marsh. It is inhabited by... beholders!
This book is loaded with encounters and weird places. It's probably the one thing you'll want if you're going to use the Ethereal.
Dragon Magazine 213 - The Demiplane of Shadow
This article is a little skimpy on details of the plane. Most of it talks about shades, including warrior shades, wizard shades, etc.
Vortexes: It is a gloomy land in perpetual twilight. In the sky above the demiplane is a vortex to the positive material plane, and a vortex to the negative material plane.
Gloomy: It is similar to a mortal world. There is weather, hills, forests, etc. It is always twilight here. Any food and water found here has no substance in which to nourish.
Creatures: We get a list of creatures that dwell here, including shadow dragons. We also get:
- Umbrimals: Natives of the plane, shadowy elemental types.
- Shades: Once-powerful mortals who tried to become immortal by infusing their bodies with shadowstuff.
"The Ethereal Plane is a Transitive Plane, a plane of getting from one place to another."
There's a few monsters linked to the Ethereal.
Ethereal Filcher: These really, really weird creatures slip into the world, steal a trinket from a person, and then slip back into the ethereal. Wow, their lair must be 5e trinket heaven.
It would be cool if there was a monster who could drag people into the Ethereal.
Dragon Magazine 313 - Ghost Elves of the Ethereal Plane
An "alien entity" called Thule appeared and offered to save the last of the ghost elves in exchange for their service. The ghost elves signed a contract with Thule, only to discover he was a pit fiend. He took them to Hell and did all sorts of terrible things to them.
He ultimately made the ghost elves into soldiers for the Blood War, which made them into great warriors. The ghost elves eventually killed the pit fiend and fled to the Ethereal Plane.
Now they live in the Ethereal plane and make war with devils.
- Ghost Elves are stern and cold. Earning their trust involves many subtle tests and trials.
- They are neutral.
- They have abandoned worship of any god.
- They despise drow.
- Ghost elves have gray hair, pale skin that glows in darkness (they can suppress this when they concentrate), and their eyes are like mirrors.
- They have hidden homes in forests on the material plane that hold secret portals to the Ethereal.
Powers: As they gain levels, they gain powers. They start off able to travel to the ethereal. Eventually they can see invisible, blink (as per the spell), and eventually shift to the ethereal at will.
Dragon Magazine 353 - Multiple Dementia: A Guide to the Demiplanes
The Black Abyss: This place is pleasant but empty and eerily silent. You drift through caverns of white stone, and you might find weird items like gems or magic items. There's a famous brass tablet with the words: "...we are safe now upon this furthest shore. The stolen gift of... Vaati...sealed and sustaining Lord Ygor..."
In the largest cavern there's a huge obelisk with the words "Time" and "Space" carved on it.
In the center of the demiplane is a swirling pool of darkness. Those who enter it vanish. Possibly to Limbo or the Negative Material Plane.
Judging from hints in this article, it seems that the obelisk is somehow related to the spawning stone in Limbo. "Ygor" might refer to Ygorl, Lord of Entropy, one of the slaad lords. The reference to the Vaati refers to the wind dukes, the blue-skinned people who try to guard pieces of the rod of seven parts.
So the slaad stole something from the wind dukes and hid it here in the ethereal plane..? Awesome.
Those who get within 500 feet of this demiplane have visions or dreams - they'll need to make saving throws or be compelled to touch the crystal. If they touch it, they are trapped inside the crystal.
The crystal moves 20 feet per round through the ethereal, under the control of the prisoner inside.
Time does not pass and magic does not function inside the crystal. The being inside can change the shape of its' prison, but not the size or mass.
A few prisoners have escaped the crystal with the aid of a wish spell from an outside party. They are completely insane.
There's a huge list of other demiplanes. Here's some of the ones I thought were cool:
- Demiplane of Haven: A city created by the mercane to compete with Sigil for the title "Hub of the Multiverse."
- Demiplane of Time: A place filled with storms and odd temporal effects.
- Neth, the Demiplane That Lives: A living, protoplasmic demiplane possessed of a childlike curiosity.