Illidan Stormrage

The War of the Ancients

A small group of night elves, including a few of the repentant Highborne, discovered what Illidan had done, and most reacted in horror. Illidan suspected the Highborne would try to usurp the Well's powers, as they had done with the first Well, and so he attacked the group. Malfurion arrived a few moments later and helped capture his twin.
He thought his people would hail him as a hero. He was wrong.

As Illidan's brother and a respected hero of the recent war, Malfurion was permitted to determine his brother's fate. Taken aback by Illidan's power, Malfurion decided that Illidan was too dangerous to be left free. Even so, Malfurion could not condemn his brother to death. Instead, he sentenced Illidan to a fate arguably far worse: Illidan was to be imprisoned for the rest of his immortal life. As a consequence of Malfurion's so-called mercy, Illidan spent the next ten thousand years in isolation, trapped in a prison far beneath the earth and guarded by the Watchers.

Lost Soul: the Third War

Proving Illidan's fears correct, the Burning Legion invaded Azeroth again during the wow gold　Third War. Tyrande, the head of the night elf government, awoke Malfurion from hibernation, and together they ventured underground to awaken the rest of the druids. In the process, Tyrande happened upon the entrance to Illidan's prison, and she decided that he would make a strong ally. Although Malfurion tried to stop her, she led her Sentinels into the prison.

 

The Watchers would not surrender their prisoner without a fight, and so Tyrande and her soldiers slew the guards who barred the way to Illidan's cell. She told Illidan that his people needed him to help fight the Burning Legion again.

Illidan consented to join the fight against the Legion. However, his long and unjustified imprisonment had left him bitter. He told Tyrande that he agreed not out of any lingering loyalty toward their people, but for her sake alone.

Free at last, he followed Tyrande upward into the corrupted forests of Felwood. Tyrande and her soldiers departed in search of Malfurion, who was awakening the last sleeping druids. She felt sure that once confronted with the reality of Illidan's freedom, she could convince her mate to give his twin another chance.

 

Once she had left Illidan alone, he was confronted by the death knight Arthas Menethil, who told him that the demons who had corrupted Felwood were using a magical artifact to do so: the Skull of Gul'dan. Arthas explained that the Lich King would be grateful if Illidan would steal the artifact from the demons. In fact, Arthas invited Illidan to claim the artifact's powers as his own.