Spent an hour figuring out this one
This is new and most likely as of wednesday, nerfed
what you do is you get your toon up on the horde roof.
When you enter you turn left the right (so you hit the eastern wood/wall thing)
Now, you see that thing that looks like a face? in the middle.
Jump in between its nose and the right eye (screenshot when i get out of college)
You just jump then tap forward (standard wall climbing)
You will be able to jump up and through the wood at the top and you land on top
Easy
Regaurds, CloWn^