System of a Down's Serj Tankian surprised the audience at The Game Of Thrones Concert Experience at the Forum in Inglewood, California by contributing his haunting vocals to the song "Rains of Castamere" in the epic clip above.
The song is infamous among Game of Thrones fans as "The Rains Of Castamere" signals the brutal, blood-soaked Red Wedding scene. The song was originally performed by The National, but Tankian puts his own spin on it with his unique vocals.
Listen to The National's version of "The Rains Of Castamere" below: