Shadowmoon Valley

Shadowmoon Valley is found in southeastern Outland, east of Terokkar Forest. It is the location of the Black Temple (where Illidan Stormrage resides), and also houses a dwarven settlement named after (and led by) Kurdran Wildhammer, as well as the prison where Illidan's former jailor, Maiev Shadowsong, is held captive. It is one of the darkest, bleakest and most fel-affected regions in the Warcraft-universe, second only to Argus. The sky is always black and ghastly yellow, lightened up by the never-ceasing rain of infernals.

Burning Crusade
Once Draenor was transformed into Outland and the Legion began to see potential in these shattered remnants, Shadowmoon became perpetually bombarded by infernals summoned by the demon lords seeking to scour any remaining life from it. When Illidan defeated Magtheridon, the leader of the Legion's efforts in Outland, and returned from his failure to destroy the Frozen Throne, these demons converged on the Black Temple and began to lay siege to it on orders from Kil'jaeden who wished to see Illidan punished for his failures. Some of these demons turned on the Legion and began serving Illidan, thanks to a mysterious source of magic within the temple and Shadowmoon became the center of a demonic civil war. Ironically, the Burning Legion began making anti-demonic weaponry themselves in order to fight the Illidari.[2]

Even after Illidan's death and the return of the temple to the draenei under Akama, it seems Shadowmoon is unlikely to recover the twilit beauty it once possessed and remains one of the grimmest reminders of what the Burning Legion is capable of.