Available: After avatar marries a character of the opposite sex.
Unlockable Character: Kana (If the main character (Corrin) is male, Kana will be a girl. Otherwise, a female Corrin will result to a boy Kana.)
The dragon veins in the map can be used to either fill up or dry out the moat. This is quite helpful if you want to delay the approach of foot soldiers. Kana will be an independent unit but will not move from her position. During the first turn, fill the first and second moats by activating nearby dragon veins. Next, place your units near key bottlenecks and end the turn. Let the enemies come and take advantage of the bottlenecks so filter their approach and allow you to block their paths with defensive units while shooting them with ranged attacks. There are also several enemy fliers here so intercept them with your archers to make quick work of them.
Like before, avoid spreading your units too far from each other and always have a healer in your smaller groups to keep everyone's HP up. Paired units will be recommended here to take advantage of the support boosts and to give you more options by having the capability to safely shelter your healers with your fighters then switch them whenever needed.