Quoted from Eskaybee:
Ok you got me intrigued! Thanks for sharing! So How do you get this stack? Is it as simple as have BFW mb lit when you start WHC? Or do you have to do something totally bizarre like start your final WIC at the Dragon shot, then light BFW, then complete your WIC which starts both?
You have to have Battle for the Wall lit, then start your 4th WIC hurry up. While its flashing, hit the dragon to start battle for the wall. Then collect the hurry up.
I started with Martell, then got the greyjoy, stark, and Martell hurry ups. Got the Lannister WIC hurry up flashing, hit the kickback, then hit the center ramp once the kickback released the ball. I think leaving Lannister for last ensures you have a nice easy shot at the start of battle for the wall to get that last hurry up asap.