Roots of Tobias Sammet

AC/DC are an Australian rock band formed in Sydney in 1973. Their music has been variously described as hard rock, blues rock and heavy metal, although the band calls it simply "rock and roll". They are cited as a formative influence on the new wave of British heavy metal bands. The band was inducted into the Rock and Roll Hall of Fame in 2003 and have sold over 200 million records worldwide, making them one of the best-selling artists of all time.

Helloween is a German power metal band founded in 1984 in Hamburg by members of bands Iron Fist, Gentry, Second Hell and Powerfool. The band has at times been called one of the most influential European heavy metal bands of the 1980s. Its first lineup consisted of singer and guitarist Kai Hansen, bassist Markus Grosskopf, guitarist Michael Weikath and drummer Ingo Schwichtenberg. By the time Hansen left Helloween in 1989 to form Gamma Ray, the band had evolved into a five-piece, with Michael Kiske taking over as lead vocalist. Schwichtenberg and Kiske both parted ways with Helloween in 1993; Schwichtenberg died two years later as the result of suicide. Between then and 2016, there had been numerous line-up changes, leaving Grosskopf and Weikath as the only remaining original members. As a septet, their current lineup features all of the surviving members of the Keeper of the Seven Keys lineup, in addition to the remaining members from the Keeper of the Seven Keys: The Legacy-era.