Knockback + Large and in Charge = ?

[Rvdvelden]

Not really sure, but as you can't follow with Knockback, aren't you limited to a 5 ft. pushback anyways, which is the same with Large and in Charge?

As far as I can see, you have 2 attempts in pushing the character back 5 ft, it doesn't really matter which one goes off first.

 

[Infiniti2000]

I see nothing in knockback that limits you to 5ft. It says you don't have to move, and it doesn't put in a restriction on the distance of the bull rush.

Additionally, LaiC is not even a chance, it's a guarantee if you hit. So, if you hit on the AoO you will move the target back the 5ft plus knock him on his ass. The knockback just might make it further (if you allow it).

 

[blargney the second]

Infiniti, that sounds almost like Awesome Blow. L&IC doesn't knock the target prone, and it does require a strength check to push them back to their last square.

 

[Rvdvelden]

Both Large and in Charge and Knockback don't put a character prone, so that point seems moot.

Furthermore, like you stated, Knockback gives a free Bull Rush attempt.
From SRD (bold added by me):

Bull Rush Results: If you beat the defender’s Strength check result, you push him back 5 feet. If you wish to move with the defender, you can push him back an additional 5 feet for each 5 points by which your check result is greater than the defender’s check result. You can’t, however, exceed your normal movement limit. (Note: The defender provokes attacks of opportunity if he is moved. So do you, if you move with him. The two of you do not provoke attacks of opportunity from each other, however.)

As you can't move with the defender using Knockback, you can't move him more than 5 feet, right?

 

[Infiniti2000]

Sorry, I really have no idea where I got the notion you get knocked prone. I must've been reading multiple rules at the same time and got confused. Thanks for setting me straight, it was just a brain fart.

 

[StreamOfTheSky]

Both Large and in Charge and Knockback don't put a character prone, so that point seems moot.

Furthermore, like you stated, Knockback gives a free Bull Rush attempt.
From SRD (bold added by me):

Bull Rush Results: If you beat the defender’s Strength check result, you push him back 5 feet. If you wish to move with the defender, you can push him back an additional 5 feet for each 5 points by which your check result is greater than the defender’s check result. You can’t, however, exceed your normal movement limit. (Note: The defender provokes attacks of opportunity if he is moved. So do you, if you move with him. The two of you do not provoke attacks of opportunity from each other, however.)

As you can't move with the defender using Knockback, you can't move him more than 5 feet, right?

Well, I've never interpreted it like that, though I suppose it could be that way. Knockback says the bull rush works like a normal one except you do not move with the target. That could be interpreted your way (you're not "allowed" to move, thus that option to push them farther doesn't work) or the way I interpret it - It's still a bull rush result, so follow all the normal results, including winning by large amounts for extra distance, except you do not move with the person. So it's more of an alteration of how normal bull rush works. You're not physically pushing them all the distance, you're just (to use a smash brothers reference) "home run batting" them away. I think the intent was my interpretation, since a) smashing people back really far is awesome visually and b) the stupid bull rush rules restrict you to a creature at most one size larger than you. So, why would the feat be giving you as much as a +2 bonus per point of power attack (if two-handing) if you only ever need to win by 1 anyway? I've used this feat on my Goliath martial rogue / barbarian, and I can tell you, by level 8, I had bonuses in the high 20's to mid 30's on a full PA (shock trooper enabled) charge attack. Winning was guaranteed against anything up to one size larger than me. All that the roll mattered for was to see if I set a new distance record. it's hard for people not focused on bull rush to have a huge modifier, so the massive +16 bonus I was getting by that level would be completely unnnecessary if the feat intended for it to be limited to 5 ft. Heck, the +8 at level 4 (when I picked Knockback up) was darn near overkill.

 

[Rvdvelden]

That's cool if you want to play that way.

I interpret Knockback as bracing yourself for impact and using the force of the onrushing opponent to move him back a bit. With a self-initiated Bullrush, you'd have much more momentum and you put all of your weight in it, so that's why you could knock somebody back more than five feet. When just standing ground, the force you generate is just not strong enough to push somebody further away.

Besides the difference of opinion, my interpretation doesn't make a mess of Large and in Charge and Knockback.