Zaruthustran said:
Question: do illusions have their own initiative score? Can they take actions?
Answer: no and no.
Conclusion: illusions can't attack, illusions can't threaten, illusions can't flank.
Please show me where in the rules it says that figment illusions (silent image, major image) can make attack rolls. Then I'll believe that they can threaten.
Everything you state here is true.
Illusions cannot be real creatures. Nobody is claiming that they can be. Illusions do not have ability scores, or the capability to make attack rolls (note the difference between making attack rolls and making attacks).
They cannot do the metagaming mechanics that an actually character can (make saving throws, roll to attack, actually cast a spell).
They can, however, PRETEND to do all of these.
Hence, they can appear to have actions and the misperception of actual "real characters" can influence the situation.
The question is: Where do you draw the line?
I draw the line at them actually physically affecting something else (with the exception of light and sound, they can affect those, otherwise they would all be transparent and totally useless).
I do not draw the line at influence. They can influence character behavior, merely based on their presence.
An illusion of a wall will be actually considered to be real until proven otherwise.
An illusion of an attacking Orc will be actually considered to be real (and threatening) until proven otherwise.
Hence, all of the game mechanic rules which apply to what we call reality in the game will apply. Threaten, flank, concealment, etc.
If the illusionary Orc stands in a doorway, he will give concealment to those standing behind him and even though arrows could pass through him, those behind him get a concealment chance to be missed.
The fact is that illusions must be able to affect the game, otherwise they are a total waste.
When it comes to flanking, the entire reason flanking is in the game is to illustrate the concept that a character who is surrounded by opponents is (typically, feats can change that) at a disadvantage in combat.
If you rule that illusions cannot flank, then by default you are ruling that a defender is not at a disadvantage due to illusionary opponents surrounding him and hence that the illusions are not perceived as real by that defender. He automatically saves against them if they are incapable of giving flank to a real character attacking that defender.
Bottom line.
As I posted on the flanking with mirror image thread, there are many situations where I would take common sense GM rulings over a literal book rule:
A B V
A B W
A B X
A B Y
A B Z
A and B are fighting. V, W, X, Y, and Z are allies of A.
V is visible. Does A get flank?
W is invisible, but neither A nor B knows he exists. Does A get flank?
X is invisible, but both A and B knows he exists. Does A get flank?
Y is an illusion, but both A and B think he's real. Does A get flank?
Z is an ugly threatening looking creature which is incapable of doing a melee attack, but neither A nor B know that. Does A get flank?
The literal book answers to these 5 examples are: yes, yes, yes, no, and no.
The common sense answers to these 5 examples are: yes, no, yes, yes, and yes.