Some ideas(Comments and criticism welcome!)

Revised basic action:
Total Defense:
Gain +4 dodge AC + 1 free nonbinding reroll on a saving throw until the start of your next turn.

(I.e. Bob the Fighter uses total defense. Max the wizard casts Color spray, but Bob can roll twice for his Willsave, picking one of the rolls that he likes.)


New basic action:
Great Blow:
As a full-attack action, you may make a single attack with +X to hit and damage, where X equals your BAB. After completing the attack, you are flatfooted until the start of your next turn.



A bunch of special abilities and/or feats could synergize with Great Blow:
I.e., if you have x/day abilities that trigger on an attack, like Stunning Fist or Smite(3.5 version), then they automatically trigger on a Great Blow without expending any resources.

A few feats that require a standard action to use like Vital strike could also be used as part of a Great Blow.

Finally, you could create a feat with 2-3 prereqs(Fighter level 8, Power attack, 18 Str for example) that allows you to perform a Great blow as standard action.


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Other:
All natural and light weapons may use Dexterity for attack rolls by default.
"Finessable" weapons may to so if you have the feat Weapon Finesse.

Weapon finesse allows you to use Dex for damage with light/natural/finessable weapons instead of Str. The bonus damage is precision damage.

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More feat revisions/new feats:
Vital strike -> Scales automatically with BAB to include the effects of Improved and Greater Vital Strike. at +11 and +16 BAB, respectively. No need for extreme feat tax as long as the new feats don't offer any new options and just increase numbers.


Weapon Focus
Prereq: Proficiency with selected weapon, BAB +1
Benefit: You gain a +1 bonus on all attack rolls you make using the selected weapon. Every feat you have that has Weapon Focus as prerequisite increases this bonus by 1.
Special: You can gain this feat multiple times. Its effects do not stack. Each time you take the feat, it applies to a new type of weapon.
((Greater Weapon Focus is removed))


Weapon Specialization
Prereq: Proficiency with selected weapon, Weapon Focus with selected weapon, fighter level 4th.
Benefit: You gain a +2 bonus on damage rolls with the selected weapon.
Every feat you have that has Weapon Specialization as prerequisite increases this bonus by 2.
Special: You can gain this feat multiple times. Its effects do not stack. Each time you take the feat, it applies to a new type of weapon.
((Greater Weapon Specialization is removed))

Weapon Mastery
Prereq: Proficiency with selected weapon, Weapon Focus with selected weapon, Weapon Specialization with the selected Weapon, fighter level 8th.
Benefit: You may take 10 on attack rolls with the selected weapon.
Special: You can gain this feat multiple times. Its effects do not stack. Each time you take the feat, it applies to a new type of weapon.


Weapon Supremacy
Prereq: Proficiency with selected weapon, Weapon Focus with selected weapon, Weapon Specialization with the selected Weapon, fighter level 12th.
Benefit: When attacking with the selected weapon, you may ignore Damage reduction and Regeneration.