Originally born a Night Elf, and twin brother to Malfurion Stormrage, he is now a Demon Hunter who mastered the arts so well it changed himself into part Demon. Because of his quest for power and mastery of the arts he committed many horrible acts against his own people, causing him to be imprisoned for 10,000 years and given the name The Betrayer. He is later released by Tyrande Whisperwind in order to aid them in fighting off of the Legion. After defeating the Legion, he forms an alliance with Kil'jaeden, in which he is given the task to seek out the Frozen Throne and destroy it. He allies himself with the Naga to help in this task. When Illidan gets to the The Frozen Throne, he duals Arthas one-on-one for it. Arthas defeats him, leaving him badly wounded, where he gets dragged off by his naga to the Outland.