John Bradley, Kit Harington John Bradley, Kit Harington

Game of Thrones waits for no man, not even a Dornishman.

Although fans may still be reeling from last week's brutal trial by combat, Sunday's episode (9/8c, HBO) will barrel ahead with yet another deadly engagement. The wildlings have made their bloody way south and are now closing in on the Night's Watch in a conflict that will test everyone's mettle. "In this battle, you see who are the men and who are the boys," Kit Harington, who plays Jon Snow, tells "Jon knows everyone's duty and he's quite prepared to sacrifice his own life for the cause. I think he's a soldier and a leader in that way."

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As is tradition with Game of Thrones, the ninth episode of the season will focus entirely on one plot, which allows for an expanded scope for storytelling. If viewers thought that the acrobatic spear fighting from the Mountain and Viper duel was innovative (watch the episode here), just wait until they see how the wildlings utilize their plus-sized allies: the giants and mammoths. "It's the most amount of green screen that we've done on Thrones," Harington says. "I've always been proud that Thrones minimizes the amount of green screen that it needs to do, but something like this with giants and mammoths, obviously we needed to use a lot of it.

"We were out there for a solid month in Belfast doing this, the battle sequence, on and off for a month," he adds. "It felt like doing a movie of Thrones, weirdly. It's the most I've been involved in a single episode by a long way. It was pretty intense."

Fortunately, the actor was already prepared for the demanding action scenes. "I had come off of a movie [Pompeii] actually where I had done an inordinate amount of swordwork, so I came into Thrones quite well prepared as far as the swordplay stuff," Harington reveals. "It's one of those things where I consider myself good at now."

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Harington's onscreen alter ego also excels at swordfighting and is known for running a man clean through — whether it's his ally Qhorin Halfhand (Simon Armstrong) or Night's Watch mutineer Karl Tanner (Burn Gorman). Harington says, "It's mad, isn't it? [Laughs] You're supposed to like Jon, but he's quite a brutal person really. He's quite sick."

How do you think the battle will play out? Will Jon survive? Who will be a casualty?

Game of Thrones airs Sundays at 9/8c on HBO. Check out a preview of "The Watchers on the Wall" below: