Succubus statblock. You get everything except the following (due to the ability being based on Summon Monster): Ethereal Jaunt, Greater Teleport, Summon. That means at will Charm Person and Suggestion as Spell-Like Abilities which "has no verbal, somatic, or material component, nor does it require a focus. The user activates it mentally." (Meaning undetectable).
You forgot Vampiric Touch and Alter Self too. Alter Self into a small form can give her +4 to stealth, +1 attack, and +1 AC and she can get extra natural attacks too. But overall the Succubus has poor damage and attack and thus little in the way of offensive potential other than spamming Vampiric Touch or charming enemies, which is not good enough. It seems the best way to leverage a Succubus in combat would be to give her a Headband of Vast Intelligence (+2) to give her 8 ranks of UMD, maybe add a Circlet of Persuasion, and have her start abusing UMD with wands and scrolls, or even staves. Come to think of it the Succubus can restore 1 staff charge per day too.
You might be better off with a Shadow Demon abusing his magic jar. Anything you beat unconscious (nonlethal) is considered a willing target, but you'll need to heal it back up afterwards. Given the advanced template his spells get +2 to DC for free, add a Shadow Stencil Set (30gp) and shadow spells get another +1 to DC, which puts him at DC21 Magic Jar, DC21 Shadow Conjuration, and DC22 Shadow Evocation. He also has at-will Telekinesis to do high amounts of damage.
It's worth noting that the Antipaladin's aura of despair gives enemies -2 to saves. With a Cornugon Smash feat he can easily get them Shaken as well. Not to mention a Conductive Scorpion Whip applying sickened (or nauseated).
On top of this is risk free Profane Gift. Profane Gift gives everyone in the party +2 to to their highest stat
No, the risk remains. Profane Gift as a Supernatural ability does not expire when the Succubus is de-summoned under PF rules (only spells and SLAs do). And summons cannot truly be killed; they just return to their home planes when they die, at which point she is free to abuse her Profane Gift to harass everyone she's Gifted with at-will Suggestion and Telepathy across planar distances (because she can explicitly use them across any
distance without any limitation applied) or even just revoke her Gift as a free action and give people 2d6 cha drain.
If being able to spam Summon Monster as a Binder breaks the game enough to make it tier 2 with that one vestige, so does being able to spam undetectable Charm Person and Suggestion.
The Binder reaches T2 because being able to spam Summon Monster gives you access to every summonable monster and their abilities. It's far beyond spamming a single monster's abilities in terms of plowing through encounters. That said, I suppose endless undetectable Charm Person and Suggestion spam can break campaigns just fine. It's somewhat comparable to a diplomancer build (although a proper diplomancer is still much better for these shenanigans). With this logic we may as well ask whether a Bard should also be marked as T2 then. He only needs 1 Spellsong feat and no one will notice him spamming his spells or abusing Fascinate to throw Suggestion performances on everybody. If you do have a Succubus around out-of-combat though, it will be an obvious trick to just spam Charm Person and Suggestion. Well, that kind of stunt is probably veering into T2 as well, although regular diplomacy abuse is better if you're going down that road.
What the heck, for now marking Fiendish Bond Antipaladin as T3 since it's certainly stronger and more versatile than a T4 but I'm not sure if it's quite T2; still he's probably T4 until level 11. Regular Antipaladin is a blue T4, because while Smite Good is much more circumstantial than Smite Evil (since a good campaign can reliably face predominantly evil enemies but an evil campaign is nowhere near as likely to spend its time fighting good enemies), a Conductive weapon lets him mix Touch of Corruption into his melee attacks making him a potent martial especially given his debuffing auras. The downside is you can't use a conductive weapon with a ranged attack, so unless the Paladin worships Baphomet in the Golarion setting for Monstrous Physique spells or uses a whip + lunge he will have an unpleasant time melee full attacking people from a distance. The easiest way seems to be playing a Human with Military Tradition for Whip and Scorpion Whip proficiencies then wield a Scorpion Whip as his weapon. If you don't use a Conductive property with a reach weapon and Lunge (or some means of pounce), he falls off a bit to a regular T4. Conductive does not work with a ranged weapon here because Touch of Corruption is a melee touch.