Castle vs. Castle is series of Rare multi-side war quests between Knights. The first one was between the Red and Blue knights, the second between the Arcane and Etain Knights, and the last one between Serlissa's and Krenos's knights. In all wars, each castle's health point started at 50 and the player had three options: a) to attack (which triggered one battle with a Random Adventure monster, and made the opponent castle lose 1 point), b) to defend (which allowed the player's own castle to gain 1 point) and c) to heal oneself. Once one of the castles reached 0, the war was over.