Ner'zhul has discovered how the rift was first formed and now covets the idea of not only reopening the gateway into Azeroth, but of creating new Portals and seeking out even more worlds to control.
You must subjugate an order of Death Knights who have secured the knowledge needed to rebuild the Dark Portal. The renegade Ogre-MageMogor, of the Laughing Skull clan, has taken control of these dark soldiers and is seeking to create a powerful spell with the aid of their necromantic magic. His life is also forfeit.
Although we have no Dragons to command, we have learned that Grom Hellscream, leader of the Warsong clan, has been captured by the Laughing Skull and is being held prisoner. Free him and he will surely aid you in your battles.
Although the mission briefing states that the player is fighting against the Laughing Skull clan, the enemy units in-game are actually colored white and aligned with the Shattered Hand clan. This may have been an error on Blizzard's part as in the next mission, the player is tasked with rescuing warriors of the Shattered Hand clan from the enemy.
While Mogor doesn't exist as a hero unit, he is presumably the lone ogre near the Temple of the Damned, but this is unclear considering this particular unit isn't even an ogre mage.
The Great Portal)
The Skull of Gul'dan
