This is much harder then the Bandit Leader. You know how much you trained for the bandit chief? Well you'll have to train that much again.
Guard Station Battle[]
This is an optional battle. This occurs if Duvalier confronts one of the Mechanics inside the Guard Station. This option is only available before you rescue the laborers. Simple enter the guard station and talk on one of the guards sitting around the table and try to get their attenion or talk to the Captains or the Marksman sitting in the chair. In the battle make sure to say out of the range of the of the Marksman. Use Luca and Griffin to distract the Captains and use Rahel's Split Shot on the Mechanic Swordsmen, Arman and Duvalier to finish off the swordsmen, and Set to distract the enemies fire from weak/in trouble teamates.
Rescuing the Laborers[]
One strategy is to make sure Arman can backstab at least 30, and survie 25 pts of dmge before you even attempt this. It is a good idea to have Luca with you at this point as she resists physical attacks like the cellar ghosts. Use her to take out the archers, but watch out. She does have the least health. Use Griffin to draw the attention of the majority of units by keeping him out in front. Rahel should be the sniper, hidden behind either a rock pile, or Griffin. Keep Duvalier and Set near the back, and near each other as they are the only two that can heal each other. Use the elemental range attack you learned because it REALLY helps, and gets stronger just about every other time you use it. Arman should be used to backstab LONE UNITS ONLY and kill them. Make sure that many other units CANNOT get to Arman's target, or are fighting Griffin. Use your head, and you should make it.
An alternative strategy is to put about 3000 gold into leveling up Set, until he gets Big and Static Shield. Field training the Hero until he gets an elemental area attack that could also come in handy. Then, in the first battle take your troops through the right side of the map and clash with all those swordsmen and crossbowmen in the bottom. Use Griffin to take on the majority of the attacks from them, use Duvalier and Rahel to deal damage with ranged attacks, whilst using Static Shield on Arman to finish off any wounded units. You can ignore the Stone Golem and Bronze Golem, after finishing with the mercenaries, surround and kill the boss: a Ravinale Swordsman. Watch out though: try not using any close range atatcks from up-front, as he can counterattack and deal unecessary damage to your teammates.
Escaping the Labor Camp[]
For this battle, try splititng your team into three parts: send Rahel and Griffin upawrds and let them take out one or two mercenaries before retreating downwards; send Arman and Set to the bottom right corner and let the assassin take out the Ravinale Guard there, whilst using the Energy Golem to your advantage; take Duvalier and Luca to the centre of the map and distract several units there, whilst using the stones to your advantage. After the first two turns or so, re-group in the centre,use Luca to block any melee attacks against Duvalier, use Set to heal any wounded units and kill off the remaining units in the centre. Finally, send Luca to the right of the map and kill the Ravinale Bowman, whilst making sure she stays out of the Energy Golem's and the Ravinale Guard's way. Then gang up the entire team on the Ravinale Guards and bring Duvalier to the needed tile.
Battle of Fawaz Gorge[]
For this battle, try taking out one or two Energy Golems with Rahel and Duvalier, whilst extensively using Static Shield on the teammates (it would help to have Rahel and Arman with high health, for instance). Then, wait for the group of two Ravinale Swordsmen with a Marksman to cross the bridge; once they do, attack them from all sides. Try to position your teammates in such a way as to ensure that the Marskman doesn't get a shot at them, as he deals 14 damage per shot. After delaying with this trio, recuperate and cross the bridge, then take out the last supporting units while trying not to stay too near Fernatus. It might be a good idea to retreat a bit, heal any wounded units, and only then surround Fernatus (from all sides so that he is immobilized and cannot use Pyro Blast), then during the next few turns use melee and indirect attacks to wittle his health down to 0. Set's Big Shield will come in handy at this stage, to nullify the effects of Fernatus' Pyro Hail. It would also be a good idea to obtain the Heat Orb before this battle, so Duvalier can resist Fernatus' fire attacks.