Particle_Man said:
Out of curiousity, if you don't allow immediate actions to occur "between" the to hit and damage rolls because that doesn't make sense in character, how do you make sense, in character, of the high level knight (phbii) 1/rd ability to take all the damage from one attack meant for an ally, which itself can be decided (will I do it for this attack?) after the attack roll (george got hit!), but before the damage roll (or did he?). Whether the latter ability is an immediate action or not, whether it is an exception or not, how would you describe it happening?
I wouldn't.
WotC is about making money. So, any "cool" idea they can come up with is fair game, regardless of how balanced it is and regardless of whether the idea makes sense from a character perspective.
With regard to Action Points, that is an idea designed to prevent character death. That is hard to do game mechanics-wise without interrupting game mechanics.
With regard to the Knight ability you mention, you'll note that it is in PHBII. The further you get from core rules, the more nonsensical yet cool (i.e. bigger, better, badder at any cost, even if it forces the players to make metagaming decisions) ideas WotC throws into the game.
DM: "Your friend gets hit."
Player: "I use my ability and take the damage instead."
DM: "How?"
Player: "Err, don't worry about it. Pretend the enemy attacked me instead."
DM: "Duh, ok."
Particle_Man said:
And would it follow that the same "in character" description could theoretically apply to immediate actions?
No, since I would not give such a description.
WotC might change Immediate Actions so that you can interrupt game mechanics with them some day, but at the moment, the only interruptions to game mechanics listed in the game are for specific special abilities.
Until they change it, I will continue to debate against metagaming rules that are not listed in the game.