"When Sargeras and the Burning Legion came to the world of Argus and began corrupting the eredar race, Velen, an eredar leader, prayed for help. The naaru appeared, offering to take Velen and any other like-minded eredar to safety. Velen and his faction accepted and began to call themselves draenei ("Exiled Ones"). The draenei hastily escaped Argus aboard the Dimensional Ship provided for them by the naaru."
"The naaru explained that there were other forces in the cosmos that would stand against the Burning Legion. One day the naaru would forge them into a single unstoppable army of the Light."
The time has come for the Army of the Light to take the battle to the enemy. The Exodar has been repaired, and the relationship between the Horde and Alliance has reached a state of tentative trust following the ouster of the dictator Garrosh. Both Velen and Wrathion have seen visions of the horrors of the Burning Legion. Of the two, Wrathion in particular supports a preemptive strike. He didn't get his ultimate wish of having a single unified faction, but an uneasy peace is close.
What better way to take the fight to the Legion than with a dimensional ship of light granted by the Naaru, mortal enemies of the Burning Legion? Who better to lead the strike on Argus than Velen and his people, who fled their home world to preserve the greater good? And who better to strike at Kil'jaeden than Velen, who loved the fallen Eredar as a brother?
We are the Warlords of Draenor, forged from the destruction that the Burning Legion wrought on that shattered world. All of our lives have been irrevocably altered by the doings of Sargeras and his minions. We will have our revenge.
To Argus!
(Here's what I'm really hoping the expansion will be - a full on battle on Argus. I think the name is Warlords of Draenor, but I think all of the information about time travel is just a red herring. What do you think?)