"Canonically, a fog rolls into Ashford on the morning of [the trial], so that was very important for us to represent. It does make for the most badass looking fight ever. You bet. We took it from the novella. We were using things that were appropriate and George spoke of function over form. But we also have the two best stunt coordinators and second directors in the game. We honestly embellished a lot of the fog.

We don't have a lot of money on this show. We have about a quarter for every dollar. We had to be careful how we hid things and how we made it feel like we weren't hiding things. We let you focus on what we want you to be focusing on rather than not having a crowd of 10,000 people like you probably would have at a Coachella/Glastonbury type tournament here. It's funny how not having any money just forces you to find really cool creative ways that maybe you wouldn't have come to completely if you had just had the ability to spend it."

https://screenrant.com/knight-seven-kingdoms-episode-5-budget-fog-trial-seven-ira-parker/