This war system is just like real Tibia's. During the war, the killing of a war opponent will always be a justified kill. However, attacking a war ponent will result in a protection zone block. If the attacked character hits back, he will also receive a protection zone block even though he did not initiate the act.
Characters that are currently in war will be marked with special icons. This allows an easy identification of friendly and opposing characters, as well as characters who are involved in other ongoing wars you are not part of.