What’s better than one expert guitarist covering a Black Sabbath classic? How about two? The Guitar Universe Tour 2014 is currently underway, and during Friedman’s set at a show in Finland on May 1, Gus G of Firewind and Ozzy Osbourne was invited onstage. The two then proceeded to play “Symptom of the Universe” because, well, why wouldn’t you? In case you missed it, Friedman also teamed up with Dave Davidson of Revocation recently.