The color of a castle's flag indicates which country controls it: green represents Caerleon, purple represents the Esgares Empire, yellow represents Iscalio, aquamarine represents Leonia, red represents New Almekia, and blue represents Norgard. Rune Knights and the monsters they control can use roads to move between their country's castles, or initiate a battle by moving to an enemy castle.
Every castle is surrounded by a unique battlefield, on which it is represented as a single hex. Any unit positioned on the castle will regenerate 100 HP per turn. The attackers' positions on the battlefield will depend on which road they used to reach the castle, and they can capture it by defeating all of the defenders' Rune Knights (or their ruler, if he or she is participating in the battle) in 12 turns. Therefore, even if the defenders are severely outmatched in battle, they can still win by stalling until the attackers run out of time.