Concealment down a corrodor

[Moriquende]

PRPG CRB Page 196 has the definition of "Concealment" as being any time "any line from [a] corner of your square to any corner of the target's square passes through a square or border that provides concealment." So what if you have a situation like this, where you are H and the monster is M?:

..XXXX
H......M
..XXXX

That's a pretty terrible depiction, but the Xs are walls and the dots are empty squares. Anyway, pick any corner of the H square to any corner of the M square and you're going to have some lines going through the borders of the wall (the X squares). So, does this monster have concealment? (It seems to me like it shouldn't, but according to the rule it seems like it would.)

Also, for a ranged attack, if you can 'see' all four corners of the enemy square there's obviously no concealment. Conversely, if all four are 'blocked' then you can't see the object. If one is 'blocked' then there is concealment. But what happens if two or three are blocked? Can you range attack an object that only has a single corner visible?

[Moriquende]

These are hard walls, so replace "concealment" with "cover" in the question above. Sorry about that. The rule for cover is the same, so I'm seeing the same problem.

[DM_Blake]

I think technically the cover/concealment rules could be read that way. However, I interpret the word "through" to not mean "along". If you pick the top corner H that is closest to M and draw all four lines to M, two of those angle diagonally down the hall to the bottom two corners of M and they don't pass through or along any walls, and the other two lines go straight along the top wall to the top two corners of M - these two lines pass "along" the top wall but they do not pass "through" that wall. Since all 4 lines are drawn without going through a square or border that provides cover/concealment, then M has no cover or concealment.

As for your second question:

There is Cover (some of target has cover but not all of it) which grants +4 to AC, Total Cover (all of the target has cover; you have no line of effect) which means you cannot attack the target, and Partial Cover (like cover, but you can see more than half of the creature) which only grants +2 AC.

There is Concealment (some of target has concealment but not all of it) which grants a 20% miss chance and Total Concealment (all of the target has concealment; you have no line of sight) which grants a 50% miss chance.

So, you're correct. If you can see all four corners then there is no concealment, no corers is Total Concealment, if you can see 1, 2, or 3 corners, it's just Concealment.

[Moriquende]

DM_Blake wrote:

I think technically the cover/concealment rules could be read that way. However, I interpret the word "through" to not mean "along". If you pick the top corner H that is closest to M and draw all four lines to M, two of those angle diagonally down the hall to the bottom two corners of M and they don't pass through or along any walls, and the other two lines go straight along the top wall to the top two corners of M - these two lines pass "along" the top wall but they do not pass "through" that wall. Since all 4 lines are drawn without going through a square or border that provides cover/concealment, then M has no cover or concealment.

As for your second question:

There is Cover (some of target has cover but not all of it) which grants +4 to AC, Total Cover (all of the target has cover; you have no line of effect) which means you cannot attack the target, and Partial Cover (like cover, but you can see more than half of the creature) which only grants +2 AC.

There is Concealment (some of target has concealment but not all of it) which grants a 20% miss chance and Total Concealment (all of the target has concealment; you have no line of sight) which grants a 50% miss chance.

So, you're correct. If you can see all four corners then there is no concealment, no corers is Total Concealment, if you can see 1, 2, or 3 corners, it's just Concealment.

Excellent reply. Thank you very much.