PFS: Tripping Fighter Build Advice needed

[Lucio]

The following is almost certainly a niche build, you get into combat, you trip everyone, and deal as much damage as possible as a result.

The general plan of attack at maximum level would be

Round 1: Spring-Attack in, trip a single opponent, take the attack of opportunity due to Greater Trip with Power Attack, trigger Cornugon Smash and then follow up with Vicious Stomp

Round 2: Cast Darkness to provide cover, and additional damage from stomping (or alternatively have a friendly caster help you out).

Round 3: Whirlwind Attack, replace attack with Trip, again additional attacks of opportunity, and vicious stomp against the prone targets.

The idea is to keep the enemy tripped and shaken to minimise the damage in return, whilst still maintaining a reasonable damage output against them. It won't be quite as deadly as a damage focused fighter, but the reducing incoming damage from those in melee (providing they can be tripped), seems a fair trade off.

One final aside, I'm assuming that the Heavy Flail offers the best weapon option, as reach weapons would impose extra conditions on where the enemies would need to be positions to be useful to you, but again looking for advice on options.

Character Build:

Tiefling Fighter 12
NG Medium outsider (native)
Init +3; Senses darkvision 60 ft.; Perception +17
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Defense
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AC 14, touch 14, flat-footed 10 (+3 Dex, +1 dodge)
hp 88 (12d10+12)
Fort +9, Ref +7, Will +5 (+3 vs. fear)
Defensive Abilities bravery +3; Resist cold 5, electricity 5, fire 5
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Offense
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Speed 30 ft.
Melee +3 silversheen heavy flail +17/+12/+7 (1d10+23/19-20) and
. . unarmed strike +12/+7/+2 (1d3+14)
Special Attacks weapon trainings (flails +2, pole arms +1)
Tiefling Spell-Like Abilities (CL 12th; concentration +12)
. . 1/day—darkness
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Statistics
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Str 18, Dex 16, Con 12, Int 13, Wis 12, Cha 10
Base Atk +12; CMB +12 (+16 trip); CMD 30 (32 vs. trip)
Feats Combat Expertise, Combat Reflexes, Cornugon Smash, Dodge, Greater Trip, Improved Trip, Improved Unarmed Strike, Mobility, Nightmare Fist, Power Attack, Spring Attack, Vicious Stomp, Whirlwind Attack
Traits armor expert, tomb raider
Skills Acrobatics +15 (+17 while in magical darkness), Bluff +2, Intimidate +15 (+17 while in magical darkness), Knowledge (dungeoneering) +17, Perception +17, Stealth +5; Racial Modifiers +2 Bluff, +2 Stealth
Languages Common, Draconic, Infernal
SQ armor training 3
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Special Abilities
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Armor Expert -1 Armor check penalty.
Bravery +3 (Ex) +3 to Will save vs. Fear
Combat Expertise +/-4 Bonus to AC in exchange for an equal penalty to attack.
Combat Reflexes (4 AoO/round) Can make extra attacks of opportunity/rd, and even when flat-footed.
Cornugon Smash When you damage an opponent with a Power Attack, you may make an immediate Intimidate check as a free action to attempt to demoralize your opponent.
Darkvision (60 feet) You can see in the dark (black and white vision only).
Energy Resistance, Cold (5) You have the specified Energy Resistance against Cold attacks.
Energy Resistance, Electricity (5) You have the specified Energy Resistance against Electricity attacks.
Energy Resistance, Fire (5) You have the specified Energy Resistance against Fire attacks.
Greater Trip Foes you trip provoke AoO when they are knocked prone.
Improved Trip You don't provoke attacks of opportunity when tripping.
Improved Unarmed Strike Unarmed strikes don't cause attacks of opportunity, and can be lethal.
Mobility +4 to AC vs. AoO provoked by moving out of or through a threatened area.
Nightmare Fist While fighting in magical darkness, you deal +2 damage
Power Attack -4/+8 You can subtract from your attack roll to add to your damage.
Spring Attack You can move - attack - move when attacking with a melee weapon.
Vicious Stomp When opponent falls prone, it provokes an attack of opportunity from you
Weapon Training (Flails) +2 (Ex) +2 Attack, Damage, CMB, CMD with Flails
Weapon Training (Pole Arms) +1 (Ex) +1 Attack, Damage, CMB, CMD with Pole Arms
Whirlwind Attack Instead of making a full attack, you attack all foes in reach.

[RainyDayNinja]

If you have the Pathfinder Society Field Guide, take the Lore Warden archetype: it gives you Combat Expertise as a bonus feat (on top of all the regular fighter bonus feats) and scaling bonuses to CMB and CMD. It also gives you extra skill points, and all Int-based skills as class skills, so you can get some good Knowledges to help outside of combat and ID monsters.