"As for Winterfell I think you'd be well aware that your greatest weapon is the cold. You could raid it as early as possible take out any armies outside the keep and stop anymore from getting in. Maybe attempt to kill some more dragons and then just leave it sieged and encircled but do not bother wasting manpower on it. The fortress would be overpopulated and given enough time supplies would run low and they'd turn on each other as well as the potential for disease to do some work. Leave them long enough and they will march out of desperation perhaps even fleeing north, starvation and winter will take it's toll and you can deal with that later."

Night King, undead, immortal, - 15 intelligence, -15 wisdom