I found this out fooling around on my level 19 mage twink. Sorry for no screens, I didn't think to take any at the time.
Alright, for the exploit: First, get on top of the Horde side tunnel (the brown/red thing sticking out into the air). Then, stand right at the very end of it, as if you are going to fall off. Once you are here, wait for an enemy to come out of the tunnel (the FC most likely) and BAM frost nova them, then flamestrike/fireball/frostbolt spam.
GG, you win. Hope you like it.
-TheWillMan