From the MMO champ home page today I saw this: http://ptr.wowdb.com/spells/146735/#17688-17807 War Banner - Increases melee, ranged, and spell casting speed by 25% 50%, and also increases damage dealt by 55% 50% for all friendly targets within 15 yards for 2 min. Instant. WTH is that? Anyone?
It is an ability used by mobs in siege of orgrimmar specifically a couple trash mobs, not a player ability.
The Add waves during the Galakras fight (and the trash before you start it around the canons) drop them.