Defending Your Castle

Defending the main castle is like the "main" mission. There will be 30 waves of enemies total, but you will also be taking enemy territory in order to unlock units/researches/gain crystals etc. in between waves.

Check out the map in between castle defense rounds. From there, you'll see how many missions you can still do before the enemies actually arrive at your castle. If the counter still isn’t at 0 (meaning 0 days until an attack), you can attempt to conquer other lands. These "conquer" missions are either siege or skirmish missions.

You have only a few days until the next wave comes to invade your home castle so you have to plan accordingly. Stop invasions that are 3 or less days away from your outposts and take other lands as much as you can before the map counts down to 0. You can just attack until you absolutely have to defend your castle if you want.

You can get experience by replaying defense waves at the home castle. Nothing happens if you lose a battle at your main castle; there's no direct penalty.