So Jon assembles the Dream Team to bring back a walker, they catch said walker only to get stuck in the middle of a melting frozen lake, The Hound being the cheeky a$$hole he is throws a rock knocking a dead muthafukkers jaw loose, throws another rock which lands on the now not melting lake letting the dead fukker see it's no longer unsafe to walk on.
Dany flies in to save the day, Night King sees dragons and asks for a spear,
not only can he resurrect the dead but apparently he would've swept every Olympic Games from here to kingdom come in the Javelin Throw. The precision with which he launched that ice spear hundreds of feet in the air through a blinding blizzard is some otherworldly shyt.
Uncle Benjen swoops in to save nephew, "on some yeah it's me, I'm kinda sorta dead but anyway get on this horse and goodbye forever.
So they succeeded in capturing an undead to show Cersei but in turn handed the White Walkers (who are pretty much bursting at the seams with an unlimited supply of soldiers" what basically equates to the Westeros version of an atomic bomb in a fukkin undead dragon.
Arya has pretty much become a gotdamn serial killer ready to take out big sis if she continues to line-step. RIP Viserion, sort of