Seems like M2tw is practically asking for a white walker invasion, with the Hoarding and Mongol scripts. Would give an extra challenge for that late game after you've conquered 6 out of the 7 kingdoms as Stannis Baratheon. LOL. YOu basically only need two units or three: A dismounted White walker, a White walker mounted on Dead Horse/Ice Spider and a bunch of wights that overwhelm the enemy. You could even have make it to where it doesn't happen unless certain conditions are met, or not met rather. (destruction of night's watch, Lack of a Stark in winterfell/ North faction wiped out, no king on the Iron Throne, etc...) I can just see it and it makes my mouth water.