If undead Benjen can’t get through the Wall, then how did that wight do it back in season one?
Remember the wight who attacked Jeor Mormont that Jon Snow killed back in season one? How exactly did that happen if wights or the undead can't get past the Wall's magic? Is it only sentient beings, like Benjen or the White Walkers, who are forbidden from crossing the Wall?
Riddle us that, George R.R. Martin.