Crazy movie (ahem, TV) magic.

The "Hardhome"  episode of Game Of Thrones was one of the  most breathtaking moments of television ever. It rivaled a movie in its scope and action, featured some of the most mind-blowing set pieces in TV history, and delivered one hell of a story punch. Here's a great video that breaks down all the VFX that was used to make the episode come to life--it's all very cool.