Rodrigo y Gabriela headlined New York’s Radio City Music Hall on Friday night. The show was part of the band’s Area 52 tour which features the expansive backing band C.U.B.A. Partway through the ensemble’s set, Testament guitarist Alex Skolnick emerged for a take on “Atman”. The metal guitarist has joined Rod and Gab onstage a few times over the years, beginning with a show at New York’s Webster Hall in 2007. Rod and Gab will perform in Boston this evening.