I am moving this over from a blog begun from a post by Mike Brock on the topic of new Animal Companion Tricks in the Animal Archive, in particular the flank trick at the suggestion of Paz (thanks Paz).
Pirate Rob wrote:
"The problem with the Animal Archive is it does change what animals can do and creates a bunch of weird situations where a player who doesn't have it plays with a GM that doesn't have it and maybe their animal flanks maybe it doesn't (up to GM) but then that player plays with a GM that does have the book and then their companion never flanks."
This seems like as good a place as any to try to get clarification of something:
One of my GMs and many of the blog contributors that I have found while researching this seem to insist that flanking has something to do with the awareness of the creature being flanked or even the awareness of the creature doing the flanking.
According to the Core Rulebook:
"When making a melee attack, you get a +2 flanking bonus if your opponent is threatened by another enemy character or creature on its opposite border or opposite corner. When in doubt about whether two characters flank an opponent in the middle, trace an imaginary line between the two attackers’ centers. If the line passes through opposite borders of the opponent’s space (including corners of those borders), then the opponent is flanked. ...
Only a creature or character that threatens the defender can help an attacker get a flanking bonus."
Nothing in the description/definition of Flanking has anything to do with awareness, only with being threatened (which also has nothing to do with awareness).
The rules governing attacks of opportunity seem to provide the best definition of a square being threatened:
"Threatened Squares: You threaten all squares into which you can make a melee attack, even when it is not your turn. Generally, that means everything in all squares adjacent to your space (including diagonally). An enemy that takes certain actions while in a threatened square provokes an attack of opportunity from you. If you’re unarmed, you don’t normally threaten any squares and thus can’t make attacks of opportunity."
It seems to me that any creature that is in a square that is threatened on two opposite sides is flanked, and any enemy character or creature in one of those flanking positions that attacks the character or creature in the flanked square enjoys the flanking bonus as long as the ally in the opposing square actually threatens - isn't unarmed or casting or something making a melee attack impossible.
What can the awareness or lack of awareness of the flanked character or creature possibly have to do with its flanked condition (or status or whatever you choose to label it)?
That was posted last night.
I was realizing this morning that the same dispute seems to go on around whether or not one of the flankers is aware of the other, for instance due to invisibility.
It seems to me that, as the definitions of flanking and threatened are written, the only person who needs to be aware that a creature is flanked, for that creature to be flanked and for the flankers to get their flanking bonus, is the GM. This should be just as true for a PC that is flanked by one or more invisible enemies, that it absolutely does not know about as it is for an enemy creature that is flanked by one or more invisible PCs that the other PC shouldn't know about but does.
Come to think of it, if two PCs had reason to believe that there might be an invisible enemy in the space between them and as a result attacked that space, even though there is probably a miss chance, they should get a flanking bonus on their respective attacks because that square is threatened by both of them on opposite sides.
I asked this question in the blog that was begun by Mike Brock in his article "Animals and Their Tricks" Monday, March 11, 2013, because it first came up for me in the context of companions and flanking and that was the only thread I could find that was specifically dealing with this topic and was started by Mike Brock, the person I would like to get the answer from.