Yesterday’s episode of Game of Thrones featured an action sequence that was simply on another level. Here’s how they did it. Spoilers ahead, obviously!

Miguel Sapochnik, who directed last season’s popular Hardhome episode, was back on board for this one, delivering Lord of the Rings-level action on a HBO TV budget.

The show’s producers have put together this behind-the-scenes look at how they made the magic happen, but be warned — the clip is dark and full of spoilers. Don’t watch it if you haven’t already seen the episode!

If you have seen the episode, though, watch the clip above and enjoy.