In this battle, your objective is to seize the throne by defeating all enemies, standing on the highlighted spot then selecting “Seize”. The layout can be a bit different since there are two windstreams that will move your units by five spaces at the end of the enemy phase. If there’s nowhere to stand, they will be moved to the nearest safe place. You can also activate this effect manually by using the dragon veins in the area though only enemy units will be moved this way.
Pay attention to the direction, position, and number of the windstreams since they change almost after every turn. You can use this mechanic to either quickly reach a new location or repositioning your units. Using a dragon vein to trigger the gust will remove the gust for the entirety of the turn so even after the enemy's turn, your position won't be altered.
There are also three chests you can loot, two to the west and one to the east. Fliers will be your best way of moving here because of their range and their freedom to traverse almost any terrain. The chest contents are the following:
It will be better if you'll move your units as a whole. And count five spaces where they'll get transferred if you're planning to use the wind streams to travel. It's also a good idea to activate a dragon vein when your units are already in a good location so that your progress won't get hampered. There are not many reinforcements that will appear in the map so it's safe to scatter single royalty units who can trigger so you can activate the dragon veins almost anywhere.
By using the windstream mechanic of the map, you can actually reach the boss in a very few turns by deliberately letting well-positioned units to be blown to the area where the boss is hanging out.