Game of Thrones is a sumptuous production if you really think about it. From the dramatic backgrounds — filmed everywhere from Northern Ireland to Croatia — to the costumes, everywhere you look there’s impressive work going on.

However, what really captures our imagination is the making of the fantasy creatures, the prosthetic piling of the White Walkers and the Children of the Forest. Indeed, the White Walkers often steal scenes (when they choose to pop up, that is), from Hardhome to when they hunted down Bran Stark and killed Hodor.

It’s easy to look past the immense amount of work that goes into creating the look of the White Walkers and, it turns out, legendary Anthrax guitarist Scott Ian was one of the freakish creatures from north of the Wall. Watch his amazing transformation below:

In the video, Ian went behind the scenes with make-up artist Barrie Gower, uncovering the immense amount of work that goes into creating each creature and the unforgettable undead look we see on the show.

Gower spoke about Hardhome, the White Walkers’ finest hour, when the Night’s King and his army took on Jon Snow in a riveting sequence that ranks as one of the finest the show has ever assembled.

“Just standing on the sidelines, just watching, you’re just thinking…’How the hell could they be getting anything from this?’ But you sort of step to one side and look at what’s on the monitor and it’s just beautiful,” Gower said.

Also, if you’re into the process of the make-up artists on Thrones, check out another awesome behind-the-scenes featurette below, focusing on prosthetics for season 6.