I was just reading one of the Nerdist articles linked above. Considering the scene in the cave, this seems very apropos.
Minor Sidebar: There are all sorts of issues with the timeline that don’t totally add up, but it is said that the Children of the Forest (whom The Last Hero contacted to help defeat the White Walkers), gave the Night’s Watch 100 obsidian daggers each year, ostensibly to fight a future invasion. Obsidian is also known as dragonglass, and is one of only two known ways to kill a White Walker. The truth is we have no idea if they did, when they did, or for how long they did, but the details aren’t as important the legend that the Children provided the Night’s Watch with weapons to defeat White Walkers for some period of time. Got it? Good.