Chapter 15C: Rainbow Sage

This is a large map with several closed rooms. The only way to reach the other rooms is by reaching the stairs. If there are enemies guarding it, you have to defeat them first to gain access. The general location of the stairs will take you the nearest room from it. That said, you have to divide your troops to two groups in order to cover all rooms. Also, other units can’t use the stairs if there’s a unit blocking it from the other side. You can only bring 9 starting units here so it's up to you if you want to divide your forces or move as a whole.

You have to deal with Nohrian and Hoshidan illusions here. There are also two chests in the NW (Spear) and NE (Spirit Katana) rooms. Bringing characters with Locktouch is optional since there is an enemy carrying the key in the same rooms with the chests. Before moving your characters into the stairs, make sure to display the enemies' attack range to avoid getting caught off guard and give them the attack initiative, especially if it will put your healers in danger.

At the end of the first turn, Shura will appear. He's already a high level advanced-class Adventurer so you have to bring your avatar to him and talk to him to recruit him in your party. He'll be a great addition to the team. At the end of the second turn, Nyx will appear from your starting position. Have your avatar approach her and talk to her to recruit her to your party.

After looting the chests, gather your forces around the stairs so that they can move in to the middle room at the same time and take out the guards around the stairs within their range. After clearing the middle room, heal up and gather your forces once again around the stairs and send your powerful units and tanks to aggro the guards in the final room. Don't send them all; just send enough to position themselves around the stairs and place your healers behind them since they don't have ranged weapons. Defeat all enemies in the final room and seize the throne when you're done.

During the chapter's ending scenes, you'll receive the Alpha Yato. Back in your castle, Jakob will arrive and join your party as well.