Yo, my mind is blown.
The Night King must've been a Greenseer, he must've.
Every attack he's done so far went perfect for him. Hardhome? 3ER's cave? Including this one.
Everything was well planned and executed almost perfectly. Now I'm convinced he waited for Bran to "visit" him and his army before branding him and destroying the cave.
I'm even more convinced after looking at that WW and his squad of Wights marching with 1 of them not even belonging to the group. It was a plant.
Then you have the spears and chains, getting himself a dragon.
HE KNEW.
Plus, I'm not sure of this yet because I'll have to revisit episode 5.
But when Bran warged those ravens and went North of the Wall,I'm almost certain that the area where they were at was the same cliff they led Jon and the squad into.