You trade away 2 Feats and take 6 levels of suck to deal 8d6+(StrMod*3) damage. To include weapon damage via Knockback you had to use a specific Race, a Race that specifically has a +1 Level Adjustment.
No disagreement there.
He blows all his Bonus Feats (pa, im-bull, 2nd & 6th ACF) plus a normal slot for Knockback, he started with 18 Str, he owns a +1 Greatsword, he deals 2d6+9 & 8d6+18 (62 avg).
The bonus feats were because I didn't use flaws, which would allow this build to go into Charger territory if so desired. Also the build uses a 1-handed weapon (for Improved Shield Bash and TWFing), although it could easily be built with a Greatsword (which is more useful until you get the Shield of the Severed Hand).
But here is the thing, there is no short list on Bull Rush modifiers. SRD's CR 7 creature data requires too much detail for me to look into tonight but a quick skim says 7 medium, 12 large, 9 huge, 1 gargantuan. That's 24% have lower, 41% equal, 34% superior without checking for stability or factoring Str. These Bull Rush attempts require a successful Attack prior to the Bull Rush check as well which further decrease chances of success.
2 Gargantuan actually. Let's test the waters.
Goliath Ranger 2/Barbarian 1/Fighter 3, so we'd be working with the lesser Dungeoncrasher at this level (4d6+12 per bullrush, averaging at 26+weapon damage per hit, with 3 attacks if using TWFing or Whirling Frenzy, 4 if using both).
Build: 15 + Knockback modifier (which varies due to enemy AC and if it gets outside bonuses like the +2 from Charging).
Gargantuan:
Gargantuan Animated Object: AC 12, BR +19/+23 (if Stability applies), 148hp
Catchalot Whale: AC 16, BR +24, 141hp
Huge:
Aboleth: AC 16, BR +16, 76hp
Huge Air Elemental: AC 21, BR +12, 136hp
Bulette: AC 22, BR +20, 94
Eight Headed Hydra: AC 18, BR +16, 87
Elasmosaurus: AC 13, BR +24, 111hp
Elephant: AC 15, BR +19, 104hp
Huge Earth Elemental: AC 18, BR +17 (+18 with Earth Mastery), 152hp
Huge Fire Elemental: AC 19, BR +12, 136hp
Six Headed Pyro/Cryohydra: AC 16, BR +15, 66hp
Huge Monstrous Scorpion: AC 20, BR +18, 75hp
Black Pudding: AC 3, BR +11, 115hp
Remorhaz: AC 20, BR +24, 73hp
Cloud Giant Skeleton: AC 13, BR +20, 110hp
Huge Water Elemental: AC 21, BR +15, 152hp
Large:
Chimera: AC 19, BR +12, 76hp
Chuul: AC 22, BR +13, 93hp
Hellcat: AC 21 (before invis), BR +14
Dire Bear: AC 17, BR +18, 105hp
Dragonne: AC 18, BR +12, 76hp
Drider: AC 17, BR +10, 45hp
Hill Giant: AC 20, BR +15, 102hp
Very Young Gold Dragon: AC 19, BR +13/+17 (depending on feat selection), 104hp
Flesh Golem: AC 18, BR +9, 79hp
Invisible Stalker: AC 17 (before invis), BR +8, 52hp
Lillend: AC 17, BR +9, 45hp
Water Naga: AC 15, BR +7, 59hp
Ogre Barbarian (Raging): AC 17, BR +14, 95hp
Young Red Dragon: AC 21, BR +15/+19 (depending on feat selection), 123hp
Criosphinx: AC 20, BR +14, 85hp
The highest modifier here is a +24, which would take a -10 penalty for the TWFing version (bad) or a -5 for the THFing version (not so bad, and easily compensated for). That enemy has an AC of 16. Do I even need to explain how easy it is to hit that thing? I don't even have the Shield of the Severed Hand active yet (and probably won't for a while, so the build would have to make do with a normal one if it wanted to use Improved Shield Bash).
At 7th level the build has very little reason to be using a shield at all, I concede that point. A Greatsword, however, would miss out on the additional attack from TWFing (and the subsequent Bull Rush + damage). I could just have him wield a Quarterstaff and abuse the RAW of Knockback (it specifies you double the bonus if using a THW, which Double Weapons qualify as even when used with TWFing).
Beyond the requisite Ring of the Forcewall (affordable at 7th level, if a bit pricy), I've done nothing with my WBL. There is room for improvement on both the feats and the equipment, but as it stands this build can contend with the Bull Rush modifiers of CR7 enemies at EL7. The damage output is questionable (it certainly can't one-round most CR7s, but it is doing an average 75hp in damage from Dungeoncrasher alone), but that wasn't the issue at hand.
I think the build has risen to the challenge.
A Generic Fighter can invest in the Shock Trooper line off his Bonus Feats alone and still have one left over. Lets add the single choice of Valorous, a Lance, Battle Jump, and Headlong Rush or Dragonborn's Dive (since specific race is on the table) rather than picking several of them. At 18 Str & a +1 Weapon that's 54 damage with a significantly high chance of success for less of an investment. Any additional traits or such will surpass the DC variant quite easily.
I'm not contending that the Dungeoncrasher is weaker than a Charger. In fact, this build has enough feats (before flaws) that it could invest in Leap Attack, Shock Trooper, and at least one other Charger feat if you want it to (and then could take flaws to get two more).
But Charging is the brokenz!
Exactly. Charging is better than DC powered Bull Rushing. It's silly to compare the two, we know who is better. The only rebuttals you can come up with is let's ignore Charging or Knockback fuels it.
You're the only one comparing them SorO.
Which is why the standard method of keeping a Fighter viable is Charging. Because his alternative - as we can plainly see from your build - takes Wands, Races, several Feats, dedicated ACFs, and apparently Relics on top of still using Charging to mange. Multiclass and PrCing provide unique methods to produce numbers without using the PHB's Bull Rush that's availability to everyone and you can do it without remaining reliant on Charging someone. In other words, the correct tone of addressing a DC Fighter build is to focus on Bull Rush by limiting your self to Bull Rush for the sake of optimizing Bull Rush. And not, DC Fighter is good so anything I make will be decent. Because thinking that means you'll be the weakest guy in the Party and as an Optimization board, we would have failed our job if we didn't mention such.
It doesn't take the Relic and Legacy Items to make the Bull Rush viable. The Ring of the Forcewall/Wands of Blockade (which only works if the enemy was already within full attack range; the ring is actually more important) are all you need as far as magic items go (on top of the usual stat boosters and weapon enhancements). Pounce is included because the enemy isn't always going to start within your melee reach (in fact, Huge enemies can charge you then sit at the edge of their own melee reach to keep you from Charging at all, as you'd provoke an AoO for trying).
And the build isn't limited to Bullrushing, it has several spare feats for additional options. If you'll notice, I also include Warblade levels in the OP to give the build something to do that isn't Bullrushing (and thanks to Knockback some of those options can still be used with it). The build obtains an IL of 15 at 20th level, which isn't the best but still gets 6th and 7th level maneuvers to work with (and 1 8th). IIRC, Lightning Throw is a 7th level maneuver.
Now then, please stop comparing it to Charger builds. I never compared it to one in the OP. Oh, and Shield Ward only applies to resisting a Bull Rush, not initiating one.