|Lava Fields||Defeat the boss|
|Ryoma||Swordmaster||Automatically at battle beginning|
|Hinoka||Sky Knight||Automatically at battle beginning|
|Setsuna||Archer||Automatically at battle beginning|
|Azama||Monk||Automatically at battle beginning|
|Scarlet||Wyvern Lord||Automatically at battle beginning|
This map has a ton of Dragon Veins that can be used to turn off and on the lines of fire running through the map. That said, these lines of fire also turn off and on at set intervals, which makes the map of this battlefield constantly changing no matter what you do. Sending any troops up the middle is just asking for them to get trapped, so work with the fire as you make your way to the northeast, where Hans awaits you.
However, we have five powerful new units to the northwest that can get in on the action immediately. Ryoma, the crown prince, and his Rajinto, will be able to steamroll through the battlefield if you so let him, and is ideal for taking on the promoted enemies if your other allies are still unpromoted (better fix that soon). Hinoka, the eldest sister, alongside her two retainers, Setsuna the Archer and Azama the Monk, suffer from having low stats for the chapter and will likely be more or less dead weight if you try to let them do the heavy lifting. So all them to sneak in what kills (and heals) they can, but otherwise protect them. Scarlet, from Cheve, is in a similar place as Ryoma: powerful and ready to go, but weak to the Adventurers and Outlaws.
Hans is a Berserker and so will hit very hard. However he has really bad Resistance so attacking him with Magic is the ideal situation. Otherwise, just gang up on him once your strongest units are regrouped, or just send Ryoma to kill him quick. Swords beat axes after all. If you fight Hans with your Avatar there will be some unique flavor dialogue.
Note: Between Chapter 16 and Chapter 17, you cannot save or visit MyCastle. So once Chapter 16 is completed you will be diving straight into Chapter 17.