From Rolling Stone by Daniel Creps

System of a Down's Serj Tankian made a surprise appearance at a recent Game of Thrones: A Live Concert Experience performance in Los Angeles to sing the series' "The Rains of Castamere."

The singer lent his unique vocals to the resounding rendition of the track, which was initially performed by the National on the Game of Thrones original soundtrack. "The Rains of Castamere" serves as the theme for the Lannister family in the popular HBO series, Blabbermouth reports.

The National's Matt Berninger also made an unannounced appearance with the production in Las Vegas Sunday night to perform the track, Pitchfork reports.

Earlier in the week, Tankian hinted his involvement with the Game of Thrones live show when he tweeted a photo with the caption, "My friend Ramin Djawadi, composer of Game of Thrones, and I playing cars? OR Prepping for the #GameofThronesLive show at the @TheForum."

In August 2016, Game of Thrones producers announced plans to turn Djawadi's score into an immersive arena experience, with the composer himself leading a full orchestra and choir while scenes from the series were shown on the big screen. The 28-date tour concludes April 2nd in Portland, Oregon.

Tankian is the latest rocker to align with Game of Thrones, although it is usually artists appearing on the small screen as opposed to the live stage: Ed Sheeran recently revealed he filmed a small role for the upcoming Season Seven, joining fellow musicians like Coldplay's Will Champion, Snow Patrol's Gary Lightbody and members of Sigur Ros, Of Monsters and Men and Mastodon to briefly transport to Westeros.

Game of Thrones returns to HBO for its seventh season on July 16th.