Greyscale has always been a mysterious illness in the world of Game Of Thrones; it's terminal, contagious, and (presumably) completely incurable. And yet, Samwell Tarly managed to figure out not just how to treat it, but to completely eradicate it in one of his new patients at the Citadel, Jorah Mormont. So how did Sam cure Jorah on Game of Thrones? With the most powerful skill of all: Following instructions properly.
Even though the characters on the show tend to treat Greyscale like a death sentence, I always kind of wondered if there there might be a way to cure it. After all, in Season 3 it was revealed Stannis Baratheon's daughter Shireen caught the disease as an infant, and somehow miraculously survived with only some scarring on her face. At the time, everybody seemed chalked this up to how Stannis invited healers from all over Westeros to treat her. But after the Season 7 premiere, a new theory emerged that her survival might have something to do with her proximity to to dragonglass, based on a book Samwell Tarly was reading in his quest to find more information about the powerful substance.
That theory ended up not being exactly true, but Samwell did find a treatment for Greyscale in his research, in a book apparently titled Archmaester Pylos On Rare Diseases. Fans saw part of the disgusting process unfold in the episode, as Samwell peeled off Jorah's scaly pus-covered skin, but there's obviously more to it than that. Luckily, thanks to HBO's Making of Game Of Thrones production diary, there are better quality images of the book Samwell was working with.
According to one of the screenshots, "exposed skin to be cleansed and soaked in a salve made from the resin of pine, the green bark of elder twigs, white beeswax and oil from the olive."
And it worked! Which it shouldn't have, according to Maester Marwyn, because it's an extremely tricky treatment to get right that a lot of Maesters haven't been able to master. Luckily, Samwell clearly seems to know the value of following tutorials to the letter. I bet he'd be really great at building Ikea furniture and making Baked Alaskas, too.
So will Samwell go around healing more Greyscale patients, now that he has this new trick up his sleeve? It's unclear what will happen next for him, but at least Jorah's free to go back and return to Daenerys in the next episode of Game of Thrones. And in the meantime, Sam will surely learn a lot useful knowledge more at the Citadel. You know what they say — knowledge is power.