DMs
In episode 4 just before she leaves for the ambush he takes her down to the caves below Dragonstone where they are mining Dragonglass.
He shows her some cave paintings on the walls that look like the spiral things we've seen earlier in the series - they are the work of the Children of the Forest a very long time ago, from long before there were Targaryens or Starks or Lannisters.
Dany says maybe they are from before there were even men, but Jon shows her a picture that has 5 small figures with 3 larger ones - the Children of the Forest and the First Men fighting a common enemy - the White Walkers - there will be another painting of them too, with the Night King.
Jon says that this shows that despite the people of Westeros differences, this shows that there has always been a need for them to bad together against this enemy.
Dany says she believes him, and that she will help him. IF he bends the knee.
It's directly after this that she gets the news that while they may have taken Casterly Rock, it hasn't exactly been a victory and their troops are now cut off.
Maester Ebrose tells Sam not to waste time trying to cure it, and mentions that an old Maester had done some reading into it but forbids Sam to take it further.
Sam steals a key for the restricted library and find the book detailing how to cut off the scales and treat it with a special ointment (that Sam prepares himself from the instructions)
We see him start the operation on Jorah, and it's clearly incredibly painful and takes all night. We don't get much more of a description of the process than that though. It's a bit underwhelming for what everyone seems to think is an irreversible condition.
Tormund will reappear in the very last scene of Ep 7 - he’s manning the Wall when the army of the dead attack and Viserion burns it. We don’t see him die or anything, just running for safety once the dragon attacks. He does. It puts him down, and while Dany is on the ground with him that's when Jaime makes a mad dash of an attack to try and kill her - Drogon turns at the last minute and blasts flame at him, and Bronn pushes Jaime off his horse (which is toast) and into the river beside him, where they see the flames burst over the surface. That's the end of Episode 4.