Shield Fighter build

[Opuk0]

I'm currently playing in a campaign with an insane difficulty level. the party currently consists of a level 5 cleric, level 6 sorcerer, level 6 summoner, level 7 barbarian, and myself a level 7 shield fighter. We're doing mythic and me and the barbarian have tier 2, the summoner has tier 1 and the sorcerer and cleric have none.

We are about to fight something with multiple death attacks in a campaign where we've regularly fought stuff with 300 hp, DR, and saves starting at +10 and going up to +15 amongst various immunities.

Is there anything I can do to maximize my shield fighter?

[Secret Wizard]

Shield Fighter can replace weapon attacks with shield attacks and viceversa while full attacking, so considering the amount of money you might have, perhaps the best idea is to go TWF and replace all your attacks with your shield's or weapon's. If you go weapon, go for heavy crits to make use of "flurry" with an 18-20 crit range weapon. If you go shield, perhaps you want to maximize all those bull rushes.

[Kazaan]

That's an interesting interpretation of the Shield Fighter ability that I hadn't considered before. Most people already know that anyone can alternate between weapon and shield using iterative attacks and it isn't considered TWF, but I haven't seen the reading that even when TWF, you can disregard the main-hand and off-hand designation and just make all your attacks with a single weapon a'la flurry of blows. And, honestly, I don't really see a logical failing in it. Nice catch on that one.

Another option is to use a Heavy Shield two-handed. No rule states you must use your shield with another weapon and a Heavy Shield is a 1-h weapon which means you can wield it in two for 1.5x Str and +50% Power Attack. ISB and PA are a must for this build.

[Opuk0]

Any suggestions for what items to buy or feats?