I actually enjoyed the Lich King fight on Halls of Reflection, where your goal was to simply get to the end before the Lich King catches up to you.
Now I actually want to see this taken up, where you have only a limited time to blow through sets of mobs and reach the end before time runs out. What do you guys think? Should it apply to a raid dungeon like after your confrontation with the source of the Sha? Or maybe after you kill Mogu Emperor Lei Shen?