Ok, this is slightly different to the post about mcing the alliance warbringer and having someone else pick him up when he gets ported outside. I can`t find a link to that but I found one that gets you up to the same spot. Heres the link:
http://www.mmowned.com/forums/wow-ex...n-dalaran.html
Basically once you get up to that spot. run to the portal in the middle of the room where the Alliance Warbringer is. ( forgot which BG it is sorry)
Once there, MAKE SURE YOUR HEARTHSTONE IS ON CD otherwise this wont work. Now you auto-unstuck while facing the warbringer. If Done correctly you should end up somewhere like here.
From there on you can 5 wait minutes then auto-unstuck again and see if you get closer. You might have to position yourself at diff angles. You have to do this because ranged attacks dont work on him for long.
Have fun, sorry if it doesnt work out.