The battle with Jon Snow and his “Magnificent Seven”-type crew—including Tormund Giantsbane (Kristofer Hivju), Sandor "the Hound" Clegane (Rory McCann), Thoros (Paul Kaye), Ser Jorah Mormont (Iain Glen), and Beric Dondarrion (Richard Dormer)—featured a huge blizzard, hundreds of undead soldiers, a giant undead grizzly bear, and a frozen lake in the middle of nowhere. Then, of course, there were the three dragons that blazed wild amounts of fire all over the place.
Because the battle raged in the harsh terrain of Westeros' far north, the production team actually sought out two locations for the film: snowy Iceland, which served as the backdrop for the icy battle environment, and a huge quarry in Northern Ireland, which doubled as a set for the rest of the battle.
Even Dondarrion's flaming sword was real.
“The sword is not CGI,” Dormer told Variety. “That’s real flames every single time. It lasts about two minutes, so I could only use it for two minutes and then it would start to go out so we had to start all over again. It was like running a marathon in about 40 kilos of armor and seal skin, with only one eye and a flaming sword that kind of blinded my one good eye. It was hellish, but it was worth it. Hard work. It took us five weeks to film that battle sequence.”
Take a look at how it was made: