Fang – Synergist Crystarium

Character Fang
Role Synergist
Fang is an interesting Synergist that can be quite effective despite having less Abilities than any other Character. She has access to Veil and Haste, but more importantly she gets the high-powered Abilities Bravera, Faithra, Protectra, and Shellra. These Abilities, exclusive to Fang and Vanille, are more powerful versions of the Abilities they are based on, but have a much shorter duration. You'll have to pay a lot more attention to your buffs if you use them, but the payoff can certainly be worth it.
Compare Fang – Synergist Crystarium to other Crystariums

Related

Fang

Eidolon Bahamut (Chapter 10)
Base HP 390
Maximum HP 24,000
Base Strength 28
Maximum Strength 2,005
Base Magic 22
Maximum Magic 1,300
Starting Weapon Bladed Lance
Primary Roles Commando, Sentinel, Saboteur
Accessory Crystal Saboteur 5
Accessory Crystal Sentinel 8
Accessory Crystal Commando 10
ATB Level Crystal Commando 8
Chapter 7

Fang – Commando Crystarium

Character Fang
Role Commando

Fang – Medic Crystarium

Character Fang
Role Medic
Fang has access to the same Medic Abilities as Lightning, but because it's a secondary Role, she's even less useful as a Medic. By the time you are likely to learn these Abilities, the lack of a Curasa spell means Fang will be terrible at healing. Her only real advantage over any other Medic is that she gets Raise (which Sazh and Snow do not), but you're more likely to use Renew or a Phoenix Down late in the game anyway.

Fang – Ravager Crystarium

Character Fang
Role Ravager
For a secondary Role, Fang is a damn effective Ravager. (This seems even stranger since she's the only Character who doesn't have Ravager as a primary Role.) She has access to every spell through tier 2, and while she only has two -ga spells, one of them is Aeroga! Perhaps her biggest disadvantage as a Ravager is that her strength is so high that she's more effective in other Roles. However, she does gain all four -strike Abilities, so even this isn't really a problem.

Fang – Saboteur Crystarium

Character Fang
Role Saboteur
Though she lacks Vanille's Death Ability, Fang is perhaps the most effective Saboteur in the game, though her one glaring weakness, an inability to inflict Poison, is a problem against many of the toughest foes in the game. She also lacks the defense-lowering multi-target debuffs (Deprotega, Deshellga, Imperilga), but as a general rule you're only attacking one target at a time anyway, so this is not a big deal.

Fang – Sentinel Crystarium

Character Fang
Role Sentinel
Like Snow, Fang has access to every standard Sentinel Ability (i.e., except Elude), though her lower HP total and relative lack of defensive Weapons makes her a bit less effective than him. She does get Mediguard first, so I guess that's something.

Hope – Synergist Crystarium

Character Hope
Role Synergist
Hope, like Sazh, eventually gets almost every basic Synergist Ability (though he gains Veil over Sazh's Vigilance). Until Chapter 10, however, Hope is primarily a defensive Synergist, with Abilities like Protect, Shell, and Bar-spells. Which of the two is more useful depends largely on how hard the enemy in question hits.

Lightning – Synergist Crystarium

Character Lightning
Role Synergist
Lightning is a surprisingly effective Synergist, gaining all of the basic Abilities with the exception of Bar-spells. Her biggest failing is not learning Haste or Vigilance until Crystarium stage 10, however. Once all is said and done, she's quite effective simply because Bar-spells aren't of much use against the toughest enemies anyway. Too bad there's no Barstone in this game.

Sazh – Synergist Crystarium

Character Sazh
Role Synergist
It takes him a while to get there, but Sazh is the most complete Synergist in the game. He and Hope have very nearly the same set of Abilities, though Sazh gets Vigilance instead of Veil. However, Sazh will first gain access to offensive buffs like Bravery, Faith, and En-spells, making him the offensive Synergist for the first nine chapters of the game.

Snow – Synergist Crystarium

Character Snow
Role Synergist
Snow is a decent Synergist as long as you don't care about elemental buffs—he doesn't get any Bar-spells or En-spells, nor does he get Veil. He does have the standard Protect/Shell and Bravery/Faith pairs, though, so he's a useful enough Synergist in a pinch.

Vanille – Synergist Crystarium

Character Vanille
Role Synergist
Along with Fang, Vanille is one of two Characters that has access to Bravera, Faithra, Protectra, and Shellra, high-powered Abilities that have a short duration to balance their extra effectiveness. Unlike Fang, Vanille has a decent number of standard Synergist Abilities as well, including Veil, Vigilance, and the Bar-spells. She is the only Character in the game that doesn't get Haste, however, so she's not very effective as your only Synergist.

Synergist

Bonus Type Extended Enhancements

Synergist

Abbreviation SYN
Role Bonus Extended Enhancements
Base Bonus (Self) None
Role Level I Bonus (Self) Duration Bonus: +15%
Role Level II Bonus (Self) Duration Bonus: +30%
Base Bonus (Allies) Duration Bonus: +5%
Role Level II Bonus (Allies) Duration Bonus: +8%
Role Accessory Supporter's Amethyst (Grants Duration Bonus: +20% to self)