Magick Cow by Jonas Myrström from the Magicka Vietnam sountrack. It only appears in the trailer for the Vietnam DLC, I did not hear it in-game. It’s a parody of The Trashmen - Surfin’ Bird. I do not claim ownership of this song, I just uploaded it because I could not find it on the internet. This is the full version. Every other upload is 30 seconds shorter.