Tuft said:
The important thing is whether the monsters knows of the consequences of the mark:
(A) Do they know about the interrupt attacks?
(B) Do they know that the Wizard still is the squshier and more easilly killed target, even when the -2 of the mark is applied?
The thing is, I suspect that the DM's choice here will make a large difference in gameplay...
(A) Yes (more below)
(B) Depends on the monster. If it is smart enough to know the difference between wizards and fighters, or at least the difference between scalemail and robes, then Yes, otherwise No.
As for knowing the consequences of a mark, the answer is easy if you apply simple deduction.
Either a combat challenge is magical, or it is not.
If it is magical, then it must work like magical powers, and the rule about knowing you are affected by a power should apply.
I think most of us would agree that it is not magical.
So, if it is not magical, then how does the fighter do it? Clearly, not by standing still and silently willing the combat challenge into effect. Much more likely he is getting in the monster's way, leaning in and bullying the monster, making himself into an obstacle.
Because of this, the fighter is basically using Aid Another to add +2 to the AC of his allies - he is interfering with the monster, making it harder for the monter to accurately attack anyone else. But, because he is making himself the target, any interference with the monster's attacks is offset by the fact that the fighter is in the monster's face and making himself an easier target - hence no net effect to the fighter's AC.
And, at the same time, by threatening the monster and putting himself in harm's way, the fighter is obviously in ideal striking range. Any monster with enough intelligence to understand even rudimentary combat tactics will realize that moving away will leave it exposed to that imposing, intimidating fighter.
Even dogs understand the rudimentary tactics of fighting as a pack, of not turning your back or your belly toward the foe, of flanking and striking from behind, of wounding the legs so the foe can't flee, and of going for critical hits, like the throat, to bring down larger foes. That's enough combat sense to know when a foe is imposing itself on you and making you vulnerable to an attack unless you face that foe and deal with it first.
So, yes, unless you're fighting something very mindless, like a slug or a fish, you should expect the monster knows what will happen if it ignores the challenge. Presumably, even brainless skeletons or mindless automatons are infused with enough magic (whatever magic animates them) to make simple decisions that improve their ability to perform whatever task they were animated to do - after all, they were almost certainly animated for combat purposes, to be guards or to be shock troops or weapons of war.
