D&D 3E/3.5 Incorporeal vs Blindsight (3.5)

[Sereg]

I've recently come across a question I can't seem to pin down the answer to, and was hoping one of you with a greater grasp of the rules might help .

Does blindsight work vs incorporeal opponents? Say, a manifested ghost (on the material plane), can he be seen/detected by the cleric with the Blindsight spell cast?



Thanks in advance,

Sereg

 

[reiella]

Erm, not sure.

But a quick question before I answer, where is this Blindsight spell?

 

[Sereg]

Well

Erm, not sure.

But a quick question before I answer, where is this Blindsight spell?

It's in a few places: Savage Species, Magic of Faerun, Players Guide to Faerun. I knew I should have had the example be a monster WITH blindsight, to avoid further confusion .

So, lets change the example: A manifested ghost on the material plane (incorporeal) vs a monster with blindsight.


Sereg

 

[reiella]

It's in a few places: Savage Species, Magic of Faerun, Players Guide to Faerun. I knew I should have had the example be a monster WITH blindsight, to avoid further confusion .

So, lets change the example: A manifested ghost on the material plane (incorporeal) vs a monster with blindsight.


Sereg

Heh actually it unforunately doesn't make it easier.

As each blindsight instance requires a specific definition of the nature of the blindsight (which is why I asked about the spell).

Lemme look up the spell though and consider that one at least. Well the spell is fairly generic and references the DMG entry [following]

Some creatures have blindsight, the extraordinary ability to use a nonvisual sense (or a combination of such senses) to operate effectively without vision. Such sense may include sensitivity to vibrations, acute scent, keen hearing, or echolocation. This ability makes invisibility and concealment (even magical darkness) irrelevant to the creature (though it still can’t see ethereal creatures). This ability operates out to a range specified in the creature description.

Blindsight never allows a creature to distinguish color or visual contrast. A creature cannot read with blindsight.

Blindsight does not subject a creature to gaze attacks (even though darkvision does).

Blinding attacks do not penalize creatures using blindsight.

Deafening attacks thwart blindsight if it relies on hearing.

Blindsight works underwater but not in a vacuum.

Blindsight negates displacement and blur effects.

Further the MM entry:

Blindsight (Ex): This ability is similar to blindsense, but is far more discerning. Using nonvisual senses, such as sensitivity to vibrations, keen smell, acute hearing, or echolocation, a creature with blindsight maneuvers and fights as well as a sighted creature. Invisibility, darkness, and most kinds of concealment are irrelevant, though the creature must have line of effect to a creature or object to discern that creature or object. The ability’s range is specified in the creature’s descriptive text. The creature usually does not need to make Spot or Listen checks to notice creatures within range of its blindsight ability. Unless noted otherwise, blindsight is continuous, and the creature need do nothing to use it. Some forms of blindsight, however, must be triggered as a free action. If so, this is noted in the creature’s description. If a creature must trigger its blindsight ability, the creature gains the benefits of blindsight only during its turn.

And from Incorpeal subtype entry.

An incorporeal creature moves silently and cannot be heard with Listen checks if it doesn’t wish to be. It has no Strength score, so its Dexterity modifier applies to both its melee attacks and its ranged attacks. Nonvisual senses, such as scent and blindsight, are either ineffective or only partly effective with regard to incorporeal creatures. Incorporeal creatures have an innate sense of direction and can move at full speed even when they cannot see.

And from the Ghost Entry

Manifestation (Su): Every ghost has this ability. A ghost dwells on the Ethereal Plane and, as an ethereal creature, it cannot affect or be affected by anything in the material world. When a ghost manifests, it partly enters the Material Plane and becomes visible but incorporeal on the Material Plane. A manifested ghost can be harmed only by other incorporeal creatures, magic weapons, or spells, with a 50% chance to ignore any damage from a corporeal source. A manifested ghost can pass through solid objects at will, and its own attacks pass through armor. A manifested ghost always moves silently. A manifested ghost can strike with its touch attack or with a ghost touch weapon (see Ghostly Equipment, below). A manifested ghost remains partially on the Ethereal Plane, where is it not incorporeal. A manifested ghost can be attacked by opponents on either the Material Plane or the Ethereal Plane. The ghost’s incorporeality helps protect it from foes on the Material Plane, but not from foes on the Ethereal Plane.

So summary.

Ghosts (non-manifest) are ethereal : Blindsight can't detect them.
Ghosts (manifest) are no longer entirely ethereal, but fully incorpreal : Blindsight is either ineffective or partially effective.

For determining blindsight effectiveness, I believe you are to consider if it's a "vocal" source, as vocal/echo would seem to fail completely based on the description of Incorpeal. Non-vocal would still typically be impeded as the 'ghost' is only there visually.

That said, there's no guidelines or description to determine what "partially effective" means.

 

[Sereg]

Aye

Thanks for going through all that, reiella, I appreciate it a lot. I have been going over the same material with even less conclusions to draw.

That said, there's no guidelines or description to determine what "partially effective" means.

This is where i'm stuck, actually. Lets say the blindsight had vibrations and scent as two of its types: What the heck does that mean vs an incorporeal creature?



Sereg

 

[reiella]

Thanks for going through all that, reiella, I appreciate it a lot. I have been going over the same material with even less conclusions to draw.



This is where i'm stuck, actually. Lets say the blindsight had vibrations and scent as two of its types: What the heck does that mean vs an incorporeal creature?

Sereg

Hmm, unless they are [Force] descriptor vibrations, I'd say it'd fail completely (they'll just pass right on through the incorpreal creature being my justification).

In fact, the only ones that I think would even be typically able to 'work' would be Dragon-Sense and other magical forms of Blindsight (such as that spell). Although for balance reasons, I'd say that spell couldn't detect them.

For partially effective, I'd use 50%, as that seems "reasonable" at a glance, and the most typical form of partial effectiveness throughout the game.

 

[rhammer2]

You are kinder than I am. I would say that blindsight, of all kinds, does not work.

Hmm, unless they are [Force] descriptor vibrations, I'd say it'd fail completely (they'll just pass right on through the incorpreal creature being my justification).

In fact, the only ones that I think would even be typically able to 'work' would be Dragon-Sense and other magical forms of Blindsight (such as that spell). Although for balance reasons, I'd say that spell couldn't detect them.

For partially effective, I'd use 50%, as that seems "reasonable" at a glance, and the most typical form of partial effectiveness throughout the game.

 

[thorian]

Blindsight based on scent wouldn't work, because incorporeal beings are scentless.

 

[Pax]

Blindsight should not work against incorporeal beings, at all, period. The concept of an incorporeal being is, there's no body there. So it can't be found by sonar, by hearing, by scent, by touch, by sensing vibrations in the air or ground, nor taste, and so on - all the things that blindsense pretty much wraps up into one single ability.

 

[Li Shenron]

Does blindsight work vs incorporeal opponents? Say, a manifested ghost (on the material plane), can he be seen/detected by the cleric with the Blindsight spell cast?

While the rules say that blindsight doesn't allow to "see" ethereal creatures, it doesn't specifically mention incorporeal creature, probably because typically incorporeal creatures are normally visible (incorporeality is effectively a lesser etherealness).

But since blindsight is basically the ability to "see without seeing", that is it relies on other senses, an invisible+incorporeal creature (which doesn't smell and isn't material) cannot be "seen" with blindsight.

Maybe there could be one single possibility: to rely on sound. If the invisible+incorporeal creature makes sound (it is inaudible unless it deliberately wants to be heard), blindsight may automatically pinpoint the creature, without the need for a Listen check. This is anyway a very particular circumstance...