[RPG] What are the limits for passing through mass with the Etherealness spell

dnd-5eethereal-planeobjectsspells

The Etherealness spell states:

You ignore all objects and effects that aren't on the Ethereal Plane, allowing you to move through objects you perceive on the plane you originated from.

When the spell ends, you immediately return to the plane you originated from in the spot you currently occupy. If you occupy the same spot as a solid object or creature when this happens, you are immediately shunted to the nearest unoccupied space that you can occupy and take force damage equal to twice the number of feet you are moved.

This is pretty straightforward for smaller objects, like weapons and items, and is discussed in What is considered an object? In this post, the bounty-winning answer cites the DM's basic rules:

For the purpose of these rules, an object is a discrete, inanimate item like a window, door, sword, book, table, chair, or stone, not a building or a vehicle that is composed of many other objects.

I assumed that Etherealness allowed travel through walls, as they are composed of multiple objects; however, this answer implies a composition of objects is not an object. Additionally, if a wall or large object like a vehicle is not an object, what is the point of the damage/ejection clause in the spell? I'd like to know what the limits are for passing through things on the Ethereal Plane. In particular, please answer the following questions with as much RAW support as possible:

  • Is it possible to pass through a building?
  • Is it possible to pass through the ground?
  • Is there anything that has mass and is neither a creature nor an object? If so, please provide examples and indicate whether it falls into an explicit class of its own, analogous to objects and creatures.

If the answer to either of the above is no, I am interested in a lore-based reason why this isn't possible.

Best Answer

A Building Is An Object

Whilst the rule you are referring to states:

For the purpose of these rules, an object is a discrete, inanimate item like a window, door, sword, book, table, chair, or stone, not a building or a vehicle that is composed of many other objects.

You have to keep in mind that this quote was taken from the Objects section and the rules the quote is referring to are about object Hit Points. The table for them only goes from Tiny objects to Large ones, it does not give Hit Points for Huge or Gargantuan objects, such as a house or a mansion (some exceptionally buildings may even be composed of several Huge or Gargantuan objects).

From page 247 of the DMG:

You can track a Huge or Gargantuan object's hit points if you like, or you can simply decide how long the object can withstand whatever weapon or force is acting against it. If you track hit points for the object, divide it into Large or smaller sections, and track each section's hit points separately.

Firstly, this shows that Huge and Gargantuan objects exist. Second, this also shows that objects bigger than Large only need to be tackled in smaller portions if you’re dealing with the Hit Points of the objects that make up a larger object.

So yes, you can pass through the ground or a building as they are both considered to be objects.

Also, in regard to this question:

Is there anything that has mass and is neither a creature nor an object? If so, please provide examples and indicate whether it falls into an explicit class of its own, analogous to objects and creatures.

Yes, Fluids - air, water, poisonous gas etc. They all have mass but they are not objects in the same way a book is an object. They are not things you could break, or grasp, or shape or manipulate, not in the same way way you could with something more tangible. A container for a fluid would be an object, but not the fluid itself.

I would argue, for the purposes of your spell, fluids do not count as objects (or, at the very least, they do not count as solid objects as they are fluids) so you could teleport into, reemerge inside them, be moved into them or whatever else you want as, because they are fluids not solids, they would move around your physical space. A fluid like water or oil might though be difficult terrain and require a swim speed, a lack of a fluid like oxygen or too much of a fluid like carbon dioxide or other poisonous gases would cause Suffocation. I don’t believe the term Fluid is used to describe things that are non-objects, non-creatures in the books but it seems an appropriate term to use.

Beyond fluids? Anything smaller than a Tiny object is not considered to be an object, anything smaller than a Tiny creature is not considered to be a creature. Perhaps Minuscule would be an appropriate term to call anything smaller than Tiny that isn’t a fluid.

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