Totally made up. I made it up for an expansion concept I've had for a while.
"She" is Azeroth, and when she stirs (ie begins to awaken), the timeless one, MUROZOND, will fear this, and begin his attempt to avert his inevitable fate.
Oh I forgot to mention. Murozond isn't dead. He pulled a Reverse Flash: what we beat in that dungeon was a time echo.