The War Mage is the last surviving member of The Order, a group of mages dedicated to guarding the 'Rifts' (magical openings between the human world and the 'Dead World' and the source of all magical power throughout both worlds). The War Mage was merely an apprentice of The Master (the oldest, most experienced member of The Order) but after his sudden (albeit apparent death) before the event of Orcs Must Die! he becomes the last War Mage, tasked with protecting the Rifts from the various onslaught of Orc attacks.
Described as being a dim-witted, foolish, stubborn and the worst of all of the apprentices by his former master, the War Mage was an unlikely last survivor of The Order. Nevertheless, when faced with the task of defending the Rifts he rises to the challenge and proves that his love for slaughtering Orcs has perhaps some skill behind it after all.