speaking of chains that reminds me about a theory I read the other day having to do with the Night King.
So some of the complaints about the "Beyond the Wall" episode revolve around
- the sudden appearance of those chains
- the preparedness of the zombies for what was supposed to be a surprise mission to capture a wight
- having weapons that can kill a dragon
- the apparent lack of urgency to kill the humans
So what if all of those issues are answered by the apparent connection between Bran and the Night King. What if the Night King knows what's going to happen because he can read Bran's mind. And if his goal was to breach the wall then what did he need - a dragon. and who has one - Dany. And who is working with Dany - Jon.
Recall back to Bran's vision in Eas****ch of the army of the dead encircled in the north - but in that case there was nobody in the middle. But it could have been a vision of what was coming.
Or the NK is simply a greenseer himself (or he's Bran in some crazy time loop - there is a theory that the NK is coming south to kill Bran to keep him from going north and becoming the NK).
Anyway they wait in a place they know they can trap Jon and his band, and then encircle them like he foresaw and wait for him to summon the dragons.
That explains why they have the dragon weapons and chains nearby apparently.
They wanted a dragon all along and laid a trap combined with seeing the future some way (thru Bran, or the NK himself). And then they had what they needed to bring the wall down - I mean otherwise they marched 1000s of miles in snow with no real plan for how to bring the wall down and just got lucky(??). I think not.