Instructions
Start with the Paradigm SYN : COM : RAV. Have your Synergist (SYN) cast Hope and Faith on the entire party to counter Mithradates' de-buffs like Poison. While buffing, have your Commando (COM) and Ravager (RAV) attack with spells only.
Switch to the Paradigm RAV : COM : RAV. The Ravagers (RAV) can attack with alternating elemental spells. Mithridates is weak to Fire, Ice, Water and Wind elemental attacks, so the bulk of the damage will come from these spells. The Commando (COM) has damage spells that can cause stagger, which can interrupt his attacks and leave him open for a round or two of free hits.
Use the Paradigm MED : COM : RAV before you are in danger of dying in order to preempt Mithridates' most damaging attacks. Your Medic (MED) can keep your party at full health so you can never be surprised by a particularly deadly spell. After fully healing your party, repeat Step 1 again to replenish your buffs.