8

Randy the Wizard needs to retrieve a sacred object that has been shifted into a demiplane for safekeeping. Randy knows that there are a number of traps and guards on the demiplane so he plans to use the Plane Shift (or Gate) spell to get into the demiplane, then cast Etherealness to bypass everything until he finds the object.

Once in its presence, he plans to quickly in succession drop Etherealness, grab the object, then Plane Shift/Gate back home.

The problem is, will this work?

The description for Etherealness says:

This spell has no effect if you cast it while you are on the Ethereal Plane or a plane that doesn't border it, such as one of the Outer Planes.

The DMG has this to say about demiplanes (p. 68):

Demiplanes are extradimensional spaces that come into being by a variety of means and boast their own physical laws. Some are created by spells. Others exist naturally, as folds of reality pinched off from the rest of the multiverse. Theoretically, a plane shift spell can carry travelers to a demiplane, but the proper frequency required for the tuning fork would be extremely hard to acquire. The gate spell is more reliable, assuming the caster knows of the demiplane.

[...] When a demiplane is connected to the Material Plane or some other plane, entering it can be as simple as stepping through a portal or passing through a wall of mist.

It's possible that a demiplane can be connected to the Material Plane, which is in turn connected to the Ethereal Border. This would also suggest that they are not part of the Outer Planes.

So would being ethereal on a demiplane work all the time? Only when the door to the demiplane is connected? DM Fiat?

MivaScott
  • 40,125
  • 5
  • 91
  • 208
  • Related: https://rpg.stackexchange.com/q/99927/38834 – MivaScott Apr 18 '19 at 18:59
  • 3
    Note that just because a demiplane (or any plane) can be connected to the Material plane doesn't mean it's connected to the Ethereal. The outer planes can connect to the Material (via Gate etc.), but they explicitly don't border the Ethereal. I don't know the answer to this question, but the fact that a (demi)plane can connect to the Material isn't part of it. – GreySage Apr 18 '19 at 19:06

2 Answers2

6

Demiplanes are located deep within the Ethereal Plane

Mordenkainen's Fiendish Folio has an entry on Xill, which contains this useful piece of information on Demiplanes:

Deep within the Ethereal Plane are the demiplanes, miniature worlds built by powerful archmages and other mighty entities to serve as a private domain. Each demiplane is a designed realm, built for a specific purpose. Some are fortresses, designed to keep wanderers from the material world away. Others are far more sinister, dark realms where evil dreams take root and become ghastly realities. [...]

As a result Demiplanes are in the Ethereal Plane, and thus Etherealness won't work while you are in a Demiplane.

illustro
  • 27,912
  • 6
  • 96
  • 171
  • From Curse of Strahd: "The land of Barovia resides in its own demiplane, isolated from all other planes, including the Material Plane." Nothing can leave Barovia, however, also from CoS: "Magic that allows transit to the Border Ethereal, such as the etherealness spell and the etherealness feature of incorporeal undead, are the exceptions to this rule. Any creature that enters the Border Ethereal is pulled back into Ravenloft upon leaving." So it looks like Etherealness would allow the user to exit to the larger space of the Border Ethereal, even if the demiplane is already in the BE. – Andrendire Mar 09 '20 at 15:38
  • @Andrendire The demiplane in CoS is a specific demiplane, it can't be used to extrapolate a general rule for all demiplanes. In the same way the fact teleportation magic in Undermountain doesn't function as it does elsewhere can't be used to extrapolate a general rule for all dungeons and teleportation in the same – illustro Mar 09 '20 at 16:14
  • I don't see why Barovia "can't be used to extrapolate a general rule." Your answer makes a blanket statement and Barovia is a counterexample to it. – Andrendire Mar 09 '20 at 16:19
  • @Andrendire because D&D 5e has the principle of specific beats general built into the core of it's ruleset. You can't use a specific exception or counter-example to postulate a general rule, because specific examples can and do have their own rules which contradict the general rules of the game. The easiest example is that of Action Surge, the general rule is creatures can only take one action on their turn, action surge gives fighters the ability to take an additional action on a turn once per short/long rest. – illustro Mar 09 '20 at 16:24
  • In this case the most general text we have on demiplanes is that they are in the Ethereal Plane (specifically deep within the Ethereal Plane). Etherealness doesn't work on the Ethereal Plane. CoS says for that specific demiplane, Etherealness does work on it, but that you get pulled back into the Demiplane of Dread when it ends. – illustro Mar 09 '20 at 16:27
  • Are Demiplanes within the Deep Ethereal encapsulated in it with borders, as their own planes, or are they part of the Ethereal in regard to their planar status? Current discussion seems to conclude that Demiplanes are separate planes which border the Deep Ethereal (like islands... with wood/stone walls...). Their form could be material (as per the rather nondescript Demiplane spell), or even elemental, depending on their origin; but it seems 1) demiplanes are their own plane 2) within the Deep Ethereal, which 3) are connected to a caster's plane when connected by Demiplane/PlaneShift – ProphetZarquon Nov 10 '22 at 04:09
  • So, a demiplane borders the Deep Ethereal & any plane they're connected to at a given time... If one wanted their own demiplane more directly 'bordering' the Ethereal Plane, I suppose they could cast PlaneShift to the demiplane from the Ethereal, but OP's question of whether Etherealness would work in a demiplane seems to have a clear-cut answer: Demiplanes are isolate planes located in the Deep Ethereal (but walled from it); demiplanes 'border' the Deep Ethereal; Etherealness works in a demiplane. – ProphetZarquon Nov 10 '22 at 04:19
2

Depends on the demiplane

A demiplane can not border the Ethereal plane like the Astral and outer planes, border it like the elemental planes or overlap like the Prime Material. Only in the last case can you do what you propose. Whether it has a ‘connection’ to the Prime Material or any other plane is irrelevant to this.

The features of a demiplane are a product of its creation - either through the deliberate choice of its creator or random. For demiplanes not created by PCs, the decision is up to the DM. For this particular DM, my ‘safekeeping’ demiplane would be selected/created so any intruders can’t use Etherealness to bypass its defenses because NPCs who utilize demiplanes are not idiots.

Jack
  • 31,646
  • 13
  • 112
  • 200
Dale M
  • 210,673
  • 42
  • 528
  • 889