However, on the hellish world of Draenor, a new Orcish army prepared to strike at the unsuspecting Alliance. Ner'zhul, the former mentor of Gul'dan, rallied the remaining Orc clans under his dark banner. Aided by the Shadowmoon clan, the old shaman planned to open a number of portals on Draenor that would lead the Horde to new, unspoiled worlds. To power his new portals, he needed a number of enchanted artifacts from Azeroth. To procure them, Ner'zhul reopened the Dark Portal and sent his ravenous servants charging through it.

The new Horde, led by veteran chieftains such as Grom Hellscream and Kilrogg Deadeye (of the Bleeding Hollow clan), surprised the Alliance defense forces and rampaged through the countryside. Under Ner'zhul's surgical command, the orcs quickly rounded up the artifacts that they needed and fled back to the safety of Draenor.

King Terenas of Lordaeron, convinced that the Orcs were preparing a new invasion of Azeroth, assembled his most trusted lieutenants. He ordered General Turalyon and the archmage, Khadgar, to lead an expedition through the Dark Portal to put an end to the Orcish threat once and for all. Turalyon and Khadgar's forces marched into Draenor and repeatedly clashed with Ner'zhul's clans upon the ravaged Hellfire Peninsula. Even with the aid of the high elf Alleria Windrunner, the dwarf Kurdran Wildhammer, and the veteran soldier Danath Trollbane, Khadgar was unable to prevent Ner'zhul from opening his portals to other worlds.

Ner'zhul finally opened his portals to other worlds, but he did not foresee the terrible price he would pay. The portals' tremendous energies began to tear the very fabric of Draenor apart. As Turalyon's forces fought desperately to return home to Azeroth, the world of Draenor began to buckle in upon itself. Grom Hellscream and Kilrogg Deadeye, realizing that Ner'zhul's mad plans would doom their entire race, rallied the remaining orcs and escaped back to the relative safety of Azeroth.

On Draenor, Turalyon and Khadgar agreed to make the ultimate sacrifice by destroying the Dark Portal from their side. Though it would cost their lives, and the lives of their companions, they knew that it was the only way to ensure Azeroth's survival. Even as Hellscream and Deadeye hacked their way through the human ranks in a desperate bid for freedom, the Dark Portal exploded behind them. For them, and the remaining Orcs on Azeroth, there would be no going back.

Ner'zhul and his loyal Shadowmoon clan passed through the largest of the newly created portals, as massive volcanic eruptions began to break Draenor's continents apart. The burning seas rose up and roiled the shattered landscape as the tortured world was finally consumed in a massive, apocalyptic explosion.