Hafthór Björnsson became famous for playing Ser Gregor Clegane, “The Mountain That Rides,” on season four of HBO’s Game of Thrones—the third actor to play the role (previously played by Conan Stevens in season one and Ian Whyte in season two)—culminating in an epic battle to the death with Prince Oberyn Martell, “The Red Viper.” But while the character he plays on Thrones is an awful beast of a man, it’s what he’s done off the small screen that has truly endeared him to the masses such as breaking 1,000-year-old viking weightlifting records while dominating strongman competitions or just being plain awesome for the kids.

Now Hafthor is taking on one of the UFC’s up and coming superstars, current interim Featherweight division titleholder Conor McGregor. The two sparred together recently, and you can see the video of their session below.

We already know that Hafthor Bjornsson, the Icelandic giant who plays The Mountain on HBO’s Game of Thrones, is a monster of a man. We also know he can be good with kids and lift a whole lot of weight.

Now, Bjornsson is breaking a 1,000-year-old Viking weightlifting record. Though “record” may be the wrong word, as it sounds more like he took on the challenge left by an old fable. While competing in the World’s Strongest Viking competition—which he won for the second time in a row—Hafthor basically carried a tree on his back that weighed in at 650 kg (over 1,400 pounds) and measured 10 m long (almost 33 feet) for five steps, besting the millennium-old legend’s three steps taken by Ormur Stórólfsson.

You can read more and see the latest feat of strength accomplished by The Mountain that Rides in the video here below, as well as an image that shows just how large the log was.