‘The demonstration has the desired effect on Cersei, shaking her in a way few things can.
Given the revelation that killing a White Walker kills the wights that it brought back, knowledge is going to be key in defeating the dead and Qyburn could be instrumental.
Game of Thrones season 7 episode 7’s incredibly engrossing Dragonpit summit was full of intriguing moments, exchanges and looks, so much so that a potentially key one got a little overlooked.
It makes total sense for Qyburn to be enchanted by The Hound’s prisoner, as the maverick maester is quite obsessed with experimenting on the dead.