Maximum potential number of bonus melee attacks with a two hander?

[Seppo87]

UnchRogue3/Urban Barbarian 12/Swashbuckler 1/????X
with Heavy Pick two handed
combat reflexes, Dex-based

Haste (+1)
Cornugon Smash + Hurtful (+1)
Come and get me, Fortuitous Weapon (up to Dex bonus +1)
Opportune Parry and Riposte (+1) (Note: uses Immediate, cannot use Hurtful next turn)

This is for a single turn. Okay, obviously no one would dare to attack this character, this is for theoretical purposes.

I was wondering if there were other things that I may have left out, more ways of getting extra attacks , or completely different builds that are better in general at generating extra attacks with a two-handed weapon

[Extra Anchovies]

Two levels of Magus can get another attack via Spellstrike Arcane Mark.

[Sayt]

Two levels of Magus can get another attack via Spellstrike Arcane Mark.

Doesn't that not work with two handing, as spell combat requires a hand free?

Personally, I'd go uMonk 11/brawler 1 with a sansetsukon:
Flurry (2)
Ascetic style(0, but enables)
Combat reflexes+greater trip+vicious stomp+fortuitous weapond (3), [may require brawler dip for counts as int 13],
Medusa's Wrath (2) [requires build support to get stunning fist operable: ki intensifying weapon or cornugon stun(weapon quality preferable), mantis style, ability focus (stunning fist)]
Ki pool (1)
Haste (1)

[legomaster00156]

Since dropping a two-handed weapon from one hand and then re-establishing grip are both free actions, yes, you can use Spell Combat/Spellstrike with a two-hander.

[Sayt]

Except to use the arcane mark Spellstrike as part of a full attack you have to use spell combat ability which specifically bans two handed weapons from being used for it.

[Ninjaxenomorph]

Wild Rager could get you the ability to get you another attack with Wild Fighting, but that doesn't work with Urban Barb.

[Seppo87]

Wild Rager could get you the ability to get you another attack with Wild Fighting, but that doesn't work with Urban Barb.
Oh, I didn't know this. I like it.
Perhaps this could be the basis for a str-based build including Martial Artist Monk (can it be unchained for the 1.5 str? I'm not familiar with unchained monk yet), or an alignment shift, to combine Flurry and Wild Fighting?

[Sayt]

Strictly speaking, no, unchained monk isn't compatible with any Archetype printed before Unchained.

Practicably speaking, Martial artist is fine, it just replaces ki pool and every ki power granted with the list ability, that said, you lose the extra attack from spending a ki point.

[Kurald Galain]

Since dropping a two-handed weapon from one hand and then re-establishing grip are both free actions, yes, you can use Spell Combat/Spellstrike with a two-hander.

No, the text of spell combat specifically disallows this.

[Barstro]

Being Mythic Tier 2 allows for an extra standard action. But that isn't really a "bonus melee attack" (and involves being Mythic, anyway).