Great episode. This review posted to counter some of the more stupidly-nit-picking reviews. No indication was given how long they were on that rock. So all these timeline complaints are nonsense. Night King has a logical reason for going for a flying dragon, if he hits it, he still has time to go for a second, since a landed dragon is slower. It's logical to go for a landed dragon last in this situation. They got the chains from the giants, and from Hardhome. Try watching the show if you want background.