Synergist is a role which mainly bestows buffs on the party, which are divided into augments and defense buffs. Sazh Katzroy and Hope Estheim specialize in Synergist, being able to learn most spells, but Sazh specializes in augments, while Hope specializes in defensive buffs.
Oerba Dia Vanille and Oerba Yun Fang are capable of learning higher tier buffing abilities, which are more potent, but less durable. However, Vanille is the only character who can't cast Haste, but has access to elemental defenses; and Fang only learns Veil beyond high-tier Synergist abilities.
Synergists received heavy changes. Haste is no longer a Synergist ability, and Serah and Noel can only learn some defensive abilities. The second tier of Synergist abilities was changed from the -ra suffix to -ga which are multi-target abilities with the same potency as the single-target versions, but with significantly lower duration. Noel can learn all Synergist defensive abilities, while Serah is restricted to the single-target defensive abilities.
The player must rely on Paradigm Pack Synergists to apply augments and elemental buffs. Lightning in the Lightning's Story: Requiem of the Goddess DLC scenario has a role based on the Synergist called Conjurer.