[3] After Necromandus, Hall collaborated with Ozzy Osbourne's first solo project after leaving Black Sabbath.

[6] The band was quickly taken up by Tony Iommi of Black Sabbath, who produced its first album Orexis of Death in 1973,[7] and invited the band to support Black Sabbath on their UK tour.

[8] When Vertigo failed to release the album, Necromandus fell onto hard times and split up.

However, the collaboration ended before an album was recorded, and Ozzy Osbourne eventually restarted his solo career with different musicians.

[9] Hall met Led Zeppelin's John Bonham through Ozzy, and the two drummers became close friends.