We've already shown you how some of the special effects for Game of Thrones were made by BlueBolt. Now another company that worked on the show, SSVFX, has also released an impressive making-of video. See it here:

Game of Thrones SSVFX Breakdowns02:44

Game of Thrones SSVFX Breakdowns

I don't know about you, but I would never have guessed that some of them were CGI.