The Fire station reduces the fire level caused by an attack or sabotage. It is one of the most important buildings that every novice player should build (and put all efforts to maximize to get -40% fire reduction) at every castle or outpost, since it will make a huge difference when playing the game at advanced levels, when you participate in many wars. One of the best advantages of having a level 4 fire station in a castle is that you will not burn at all when an attacker does not have "fire damage" commander. The total of fire station (-40%) with a good "fire castellan" (-75% + 10-15% from hero) combined with completion of "fire pump" research (-15%) and also (optional) a "Firefighter" ability in your "Hall of Legends" defense, you can have over a 100% fire reduction.