D&D 5E Combat & Etherealness

[LordEntrails]

Looking for some thoughts or more RAW on how combat between material and border ethereal opponents might take place. The only thing I can find (DMG) is that "certain effects and magical force" can harm opponents on the border ethereal.

So, given an enemy NPC on the border ethereal (say something similar to a ghost) choses to attack the party. if the NPC stays in the border ethereal, how can the party harm it? Magic Missiles seems right there, whatever magical force damage is there? But how else? Magic weapons? Silver? Other spells? Which ones?

Now, assume the NPC can shift out, attack physically, shift back; then the party could ready attacks. Any special rules or considerations for this? (resistance, saves, check to time it well enough?)

 

[Charlaquin]

Most effects that shift a creature to the ethereal plane state that the creature can’t affect or be affected by anything on the material plane. I think an effect would need to specify that it could affect target’s on the ethereal plane from the material plane (or vise versa) to get around this restriction.

 

[Guest 6801328]

On a related note, does blindsight let you see ethereal creatures?

 

[R_J_K75]

On a related note, does blindsight let you see ethereal creatures?

Your blind you cant see period.

 

[R_J_K75]

So, given an enemy NPC on the border ethereal (say something similar to a ghost) choses to attack the party.

Pretty sure that in order for either to physically attack one another they have to both be on the same plane. IIRC creatures on the border ethereal can see into the prime material and creatures on the prime material can see creatures in the border ethereal, some attacks such as a ghosts aging effect may penetrate the prime material from the border ethereal. Its been a really long time since I've thought about it and things may have changed in 5E, but think Im close.

 

[Iry]

Your blind you cant see period.

 

[R_J_K75]

As a DM in this situation I would rule that as an ethereal creature a ghost even manifested on the material plane is still incorporeal so youd actually need sight to see it. Now if the ghost had other forms of manifesting besides visual, say a sound, smell, gust of wind or change in temperature then sure a creature with blindsight could detect it. But a creature with blindsight would be immune to a ghosts horrifying visage.

 

[prabe]

On a related note, does blindsight let you see ethereal creatures?

I think that would depend on how the blindsight is defined/explained. Something like sonar? You're probably not detecting the ghost. Some sort of mystical ability that allows you to sense disturbances in reality caused by life and unlife alike? Sure.

 

[Flamestrike]

Looking for some thoughts or more RAW on how combat between material and border ethereal opponents might take place. The only thing I can find (DMG) is that "certain effects and magical force" can harm opponents on the border ethereal.

The Border Ethereal is still the Ethereal plane; it's just close to the Plane you're viewing (in this case the Material), allowing you to vaguely perceive into that plane.

For something to perceive or effect you, the spell, effect, creature or ability has to expressly be able to cross into the Ethereal plane to affect you on the border ethereal.

For example the spell Etherealness expressly shunts you to the border ethereal:

You step into the border regions of the Ethereal Plane, in the area where it overlaps with your current plane. You remain in the Border Ethereal for the Duration or until you use your action to dismiss the spell. During this time, you can move in any direction. If you move up or down, every foot of Movement costs an extra foot. You can see and hear the plane you originated from, but everything there looks gray, and you can't see anything more than 60 feet away.

While on the Ethereal Plane, you can only affect and be affected by other creatures on that plane. Creatures that aren't on the Ethereal Plane can't perceive you and can't interact with you, unless a Special ability or magic has given them the ability to do so.

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Also, no general rule allows force damage to penetrate the Ethereal plane:

Sage advice confirms this.

Force damage simply affects 'ethereal' type (read: incorporeal) creatures better than most other damage types. Things like Banshees and Ghosts and so forth are resistant or immune to most forms of damage, other than Force and a few others.

Truesight (and the True seeing spell) lets you see into the Ethereal plane. Forcecage, Leomunds Tiny Hut and Wall of Force both extend into the Ethereal plane just fine as well (so a Wizard with True Sight active or a spellcasting creature with Truesight could entrap a creature on the Border ethereal watching him with one of those spells).

Mordenkainens Magnificent Mansion, Demiplane and Rope Trick protect you from being perceived by creatures on the Border Ethereal seeing as you're no longer on the Material plane when you enter the Mansion, Demiplane or extradimensional hole at the top of the rope respectively.

When a Ghost is on the Material plane, it can be affected normally by creatures on that plane, however it is immune or resistant to most attacks - notably barring Force and Radiant effects. When it uses its etherealness ability to retreat to the Ethereal plane it remains visible in the Material (and can see into the Material) by virtue of that ability, but loses the ability to affect anything or anyone on the Material (no possession, no horrifying visage etc).

 

[Flamestrike]

When the DMG refers to 'force' effects in its description of the Ethereal plane its referring to (most) force barriers. Not the force damage type.

Ghosts cant pass through a wall of force for example and neither can an ethereal Wizard.

But a Wizard with true seeing active, who can thus see into the Border Ethereal cant also target a creature in the Ethereal/ Border ethereal with spells, (even force effects, barring Forcecage) even though he can see the Ethereal creature.

He would need to enter the Ethereal plane, and then its fair game.

Ditto a Solar (who has Truesight and a Perception of +14) on the Material plane. He would notice a 'nearby'** Ethereal creature, but cant affect it with any of his abilities.

Hang on. Solars cant plane shift on their own. How hilarious! I suppose they have Deities doing that for them, but that seems an oversight to me.

** 'Nearby' is a misnomer. The Ethereal creature is actually an infinite distance away, on an entirely different plane of existence.