Background:
Walls in particular, but also to a lesser extent doors, are not ever actually defined by the rules. While at first glance, things seem simple enough, it is relatively common for players to ignore the internal wall-lets created when large rooms connect (which is fine for their games, until someone disputes...) but there are a small number of issues created by the lack of a clear definition for walls and doors.

To be honest, the last FAQ ruling that some effects do pass through (closed) doors actually worsened the problems.
Sample issues include:
i) Grapple, Aura etc extending through closed doors (adjacency is not blocked by doors).
ii) spaces on opposite sides of a wall, but connected at one corner only (see diagram, C and D) are technically adjacent. So although effects which rely on LOS will be blocked (eg Blast) effects which rely on adjacency will not (eg SoBs exploding skeletons, Grapple, Aura etc). Further, a figure with a radius effect like command may be able to use the breath + template example system to 'count' EDC (3 spaces) even though the effect passes through a solid wall and probably should count EDAC (four spaces).
AB
C|DEF
iii) Runewitch Astarra, in a SoB campaign, has been able to activate Glyphs behind close *and rune-locked* doors before the heroes get to a runekey. Maybe that's fine, but I suspect that goes far beyond what was intended!

Question1:
What do walls block?

Potential Answers
A1-1. Walls block everything. Walls block LOS. Walls block attacks. Walls block effects. Walls block adjacency (two spaces with a wall between them may not be considered adjacent) and walls block anything we haven't thought of yet. Walls may not be moved through under any circumstances. Walls may not be measured through for any purpose.
A1-2. Walls block LOS. Walls block attacks. Walls block effects. Walls may not be moved through under any circumstances.
A1-3. Some other clear combination.

Question 2:
What do closed doors block?

Potential Answers
A2-1. Closed doors may be treated as walls. (Note that this may be a change from the previous FAQ ruling, depending on the answer to Question 1 above).
A2-2. Closed doors block (pick and choose from the list) Movement, Attacks, LOS, Adjacency (two spaces with a door between then are not considered adjacent), affects with a radius. Closed doors do not block (pick all not picked from the list before).
A2-3. Closed doors may be treated as walls except they do not block (...).

Discussion notes (for us, not FFG)
This is quite a biggie, and I suspect FFG will probably bury their head in the sand and ignore it, but I do believe we should try at least. The answers are very simple if they are willing to change the last FAQ ruling and only slightly more complex if they are not. I think the complete list of things that must be considered is
1. Movement
2. LOS
3. Attacks
4. Adjacency
5. Effects with a range

But feel free to add in anything I've forgotten.

It is also possible that the reference to the breathe/template system for command might clash with the previously defined 'big square temple' 'radius' ruling in the FAQ. I am not sure whether we should drop this reference entirely, or watch it carefully.

Corbon said:

I think it would be wise to define what qualifies as an attack vs an effect with range for this purpose (and in general for all purposes, really.) Is Aura an attack? Is grapple? I'm inclined to think of any effect that causes damage to a figure as an attack, but that's probably not supported in the rules.

Corbon said:

I don't think this question should be ignored. Even if the final answer is "the difference doesn't matter based on other rulings." It should be explicitly clarified to prevent certain people from getting uppity about the fact that it's not explicitly clarified.

If you want the door and wall rules to be technically complete, you almost certainly also need a special rule for the "joint" between a wall and a closed door. Line-of-sight isn't blocked when it only touches something at an edge, and there's a point there that touches the edge of the wall and the edge of the closed door without passing through either one, so without a special-case rule, technically, some things can almost certainly slip between them, which is almost certainly not intended.

From a less pedantic perspective, we need a ruling whether the "joint" blocks things as if it were a wall or as if it were a closed door.

Steve-O: Only things that explicitly claim to be attacks are attacks, and all attacks are governed by the "Attacking" rules (p.9-11) except where they explicitly create exceptions to them. Any other definition is asking for trouble. Unlike "movement", the word "attack" does not yet have multiple technical definitions in Descent; let's try to keep it that way.

Aura and Grapple are not attacks, they fall under the "adjacency" category Corbon listed. Even constrict and exploding skeletons are presumably not attacks, even though they roll dice and cause damage, and constrict is used in place of an attack. But a Leap attack is an attack because it says it's an attack, even though it also overrides some of the normal attack rules.

Yes I agree it would be nice if we could get a definition for walls and closed doors, though FFG will most likely just ignore it as Corbon says, it'd be good to at least try to get a straight answer.

Honestly, I think it would just be simplest if they said that walls blocked everything, and closed doors act like walls. That would be simple and easy to remember, nothing gets through. Plus like the Runewitch Astarra example in the SoB campaign that Corbon mentioned, I'm pretty certain it wasn't intended for one character to basically negate the whole point of levels like that.

Is there any reason FFG wouldn't want to do that? Other than the fact that it represents a change from previous rulings of course, but they've done that in the past. What I mean is, would having walls and closed doors act the same way, and block all game effects create some unforseen difficulties? Or other wierd rule situations? I'm just trying to understand why they made it so strange in the first place.

Antistone said:

Perhaps an extra line that attaches to all answers for question 2.
"Joints between walls and doors are treated as if part of the door"

That seems simple and clear?

Hmm, still doesn't solve the adjacency-through-the-wall issue when the door is open. Maybe that needs a separate and explicit statement?

Corbon said:

Perhaps change adjacency rules to say that two squares must share an edge (orthogonally) or a corner (only diagonally) to be considered adjacent? That might be getting too nuanced for some example situations, though. Also not sure if it would have any unforeseen effects on things like movement or attacks of large monsters.

Revised

Background:
Walls in particular, but also to a lesser extent doors, are not ever actually defined by the rules. While at first glance, things seem simple enough, it is relatively common for players to ignore the internal wall-lets created when large rooms connect (which is fine for their games, until someone disputes...) but there are a small number of issues created by the lack of a clear definition for walls and doors.

To be honest, the last FAQ ruling that some effects do pass through (closed) doors actually worsened the problems.
Sample issues include:
i) Grapple, Aura etc extending through closed doors (adjacency is not blocked by doors).
ii) spaces on opposite sides of a wall, but connected at one corner only (see diagram, C and D) are technically adjacent. So although effects which rely on LOS will be blocked (eg Blast) effects which rely on adjacency will not (eg SoBs exploding skeletons, Grapple, Aura etc). Further, a figure with a radius effect like command may be able to use the breath + template example system to 'count' EDC (3 spaces) even though the effect passes through a solid wall and probably should count EDAC (four spaces).
AB
C|DEF
iii) Runewitch Astarra, in a SoB campaign, has been able to activate Glyphs behind close *and rune-locked* doors before the heroes get to a runekey. Maybe that's fine, but I suspect that goes far beyond what was intended!

Question1:
What do walls block?

Potential Answers
A1-1. Walls block everything. Walls block LOS. Walls block attacks. Walls block effects. Walls block adjacency (two spaces with a wall between them may not be considered adjacent) and walls block anything we haven't thought of yet. Walls may not be moved through under any circumstances. Walls may not be measured through for any purpose.
A1-2. Walls block LOS. Walls block attacks. Walls block effects. Walls may not be moved through under any circumstances.
A1-3. Some other clear combination.

Question 2:
What do closed doors block?

Potential Answers
A2-1. Closed doors may be treated as walls. (Note that this may be a change from the previous FAQ ruling, depending on the answer to Question 1 above). Joints between walls and doors are treated as if part of the door
A2-2. Closed doors block (pick and choose from the list) Movement, Attacks, LOS, Adjacency (two spaces with a door between then are not considered adjacent), affects with a radius. Closed doors do not block (pick all not picked from the list before). Joints between walls and doors are treated as if part of the door
A2-3. Closed doors may be treated as walls except they do not block (...). Joints between walls and doors are treated as if part of the door

Question 3:
Can a space be adjacent to another space if there is a wall between them?

Potential Answers
A3-1. Yes. As long as two spaces share any corner they are adjacent. This means that you can be affected by adjacency (eg grappled) even when you are unable to attack through a wall sometimes.
A3-2. No. To count as adjacent two spaces must draw a line between their centre points that is not blocked by a wall or closed door ("or closed door") depending on other question answers) .

Comments:
Improved? Anything to add or change before inclusion in the FAQ Proposal Document?

Probably A2-2 could be simplified, since we already know from the rules that doors block all attacks, movement, LoS - so FFG doesn´t have to reconsider those if they are left out.

According to the FAQ even radius effects seem clear, but it might be a good idea to reclarify especially with the Astarra background.

This leaves adjacency as the main focus.

A2-3 to me looks pretty similar to A2-2 and can probably be removed.

The answer part regarding the joints between doors and walls will most likely confuse FFG, since they are not mentioned or explained in the background.

Finally, the background example ii) might give a false impression or lead: EDAC for a Command counts four spaces, yet it is perfectly within the template of length 7, so everything is fine here (the actual distance traveled on the template doesn´t matter) - unless there is no path from the Command centre to the target space, of course.

Parathion said:

My thinking is that if we are going to do a list it ought to be definitive, else it introduces the question whether leaving something out was an intended 'change'.
I don't think leaving them in can hurt, and it could possibly harm.
Still object? (even if that isn't the right term)

Parathion said:

Indeed. The older FAQ - radius answer has created some unnecessary issues at times. If this forces them to reconsider, I think it would benefit the game - which ever way they choose.

Parathion said:

Agreed, they are very similar.
A2 is the definitive list. However, depending on the answer for Q1 though, it may be a lot easier and save space to use A3, and just treating closed doors as walls simplifies things a lot (especially for the future) - if they are willing to go there.
Either way, they'll pick one, so I don't see the harm in leaving both options?

Parathion said:

I'll add Antistones comment to the background section later.

Parathion said:

As for A2-2. we can leave it as a definitive list, but probably add a note that "movement, attacks, LoS" are already clear as per the rules. No objections.

A2-3. Add that this may be a simpler answer to select, depending on the answer to Q1. Might save them a bit brainpower

Regarding Astarra / Command, it might be could if they reconsidered all abilities, so maybe we leave it in but reword it to avoid conflict with current FAQ radius effects ruling.

A3-2 presents a problem. Say a hero gets the skill that grants him/her the grapple hability. Now this hero goes to a corner which is adjacent through a wall to another space. Then a naga goes to that other space. The hero is grappled by the naga, the naga is grappled by the hero and none can attack each other.

I think the pit ruling was changed due to this sort of problem, so why sould it be different here?

If I picture the situation you described correctly, then I don´t see the problem - both figures would not be adjacent and thus Grapple would not work. Please explain e.g. with a diagram if you still see a problem.

Small addition to the adjacency question (Q3) in combination with the Alertness skill (are there similar SoB skills or feats):

There are two examples that I can think of that lead to adjacency without a figure actually entering an adjacent space:

1) Two figures are on opposite sides of closed doors, then the door is opened.

2) Soaring figures swooping down next to a figure.

Would these trigger an Alertness attack? RAW it wouldn´t, since the figure did not enter a space adjacent to the Alertness hero, rather it has been there before, but just wasn´t adjacent.

Parathion said:

In both cases the figure entered the adjacent space earlier.
That would trigger Alertness for the Soar, and a hero could make an attack against the Soaring figure (obviously a melee attack isn't possible). Alertness does not require the figure to be adjacent, just to enter an adjacent space.

The door is slightly different, but again, Alertness is triggered on entering the adjacent space. If the space is not adjacent at the time due to modified door/wall rules, then Alertness isn't triggered. If the space is adjacent, then alertness triggers but the attack is blocked.

I don;t see anything uncertain or unclear there that isn't already covered (ie, the only unceratin thng is adjacency through te door, which is coverd by eth existing question). AFAICS Alertness and any similar Feats don't bring any new questions to the table here.

great to see the clarification