After freeing our old friend from Anankos's control, we find another familiar face that is a puppet of Anankos.
Defeat the Boss
To reach the boss unit in this map, you will need to activate the three Dragon Veins in order to access the boss's room.
Your units will be split into two groups from the start. You will need to all get into the small room that shows up at the start of the battle. You should pair up your units so that everybody will fit.
The rooms will move at the end of each enemy phase. However, keep in mind that a room won't move if anyone is standing in the doorway of that room. Each door is really a double door, so anyone standing in the path of either of those two doors will prevent the room from moving.
After you have loaded everybody into a moving room, your northern group will be able to reach the northern area, and your southern group will be able to reach the middle area.
After each group deals with the enemies in the area, activate the Dragon Veins.
After the northern group has activated their Dragon Vein, they should go to the northeast corner of the map, killing enemies on the way, and then wait there for the southern group to activate the middle and southern Dragon Veins. However, check the movement rates of the enemies in the boss unit's room. The boss's room will start moving after the Dragon Veins are activated, and it will eventually open up at the three doors south of the northwest corner. To avoid being rushed by the enemies in that room, stay far enough away from those doors that you won't be in range of the enemies there when those doors open.
Once the southern group activates the middle Dragon Vein, have them get into the southern moving room when it comes close, then wait until it opens up into the southern area. Deal with the enemies down there and activate the Dragon Vein.
After that, the boss unit's room will start moving up and down. It will alternate opening up to the northeast corner and the southeast corner. Make sure to move your units into position so that they can access the boss's room when it opens up in their area.