War Banners are consumable items that drop as random loot from monsters in contested areas.
When used, War Banners apply a special buff that allows the player and all nearby allies to attack enemy players that have their Flag of War turned off. This buff lasts for 1 hour and will disappear on death. The player cannot lower their flag or remove the buff by right-clicking it. If you leave the zone that the banner was made for, a 1 min timer will count down and remove the buff if you don't return to the zone. The effects of the banner can stack with other banner carriers. While active, the location and name of the carrier will also be displayed on the map.
The item itself has a 20 min timer when picked up. The item cannot be used outside of the designated zone, it cannot be stacked, and it will disappear from your inventory after the timer expires (timer continues even while offline). This item is bound on pickup. This item is special in that a high-level player can still occasionally obtain them as drops even when killing mobs that are normally out of level range for dropping items.