After a practice battle, you are brought before the king of Nohr.
Rout the Enemy
The victory condition for this battle is to Rout the Enemy. When you first start the battle, walk onto the Dragon Vein and choose Dragon Vein to clear the debris. Only Corrin can do this.
The healing area is a 3x3 square. As long as your units stand on these tiles, they will regain HP on each turn.
Put Jakob in the center of the square, because his weapon has a range of 2, so he can attack the enemies even if you put Corrin and Gunter to his left and right.
Put Corrin on the left side and Gunter on the right. Make sure that they are still standing on Healtiles. We are putting Corrin on the left because Corrin has a red weapon with a green stripe at the bottom, which means that it is more effective against green weapons, and Rinkah has a green weapon. Rinkah's weapon has a blue stripe at the bottom, which means that it is more effective against blue weapons, which is what Gunter has, so he should be on the right to avoid Rinkah's attacks.
In Lunatic mode, you will need to protect Jakob/Felicia from taking too much damage. Focus on getting rid of Kaze and Rinkah as soon as possible. But be sure to make Jakob/Felicia gain some levels during this chapter so that he/she can provide enough support in the next one.