This battle is easy as the boss has no special moves; he may occasionally use Break, petrifying its target, and can cast Protect to reduce physical damage. He frequently casts Bio on a random party member or the entire team, which may inflict Sap. Although he does not pose much of a threat, he is supported by 2 Weresoldiers X, and they can damage the party with normal attacks, Thwack and Claw.
The party should eliminate the boss's allies to reduce the incoming damage, using Gold Needles to heal petrified party members. Support abilities, such as Matoya's Cure Waltz, are best for keeping the party alive. A Red Mage's Attune Blade, or any attacks and skills that deal a high damage, should end the fight quickly and easily.