Day of the Dragon
Very little is known of the Burning Legion except that the wars of modern history are due to their influence. Thousands of years ago, they directly invaded the land of Azeroth and were beaten back at a terrible price. The world continues to fear their return. They are a vast, innumerable army of demons, infernals, and corrupted races who seek to destroy any trace of order in the universe. Much of Azeroth's history is due to the Legion's influence. It should also be noted that Azeroth is the only known planet that they have ever failed to conquer.