Vocal:
Rasmus Bom Andersen (Diamond Head) - Symptom Of The Universe
Steve Sylvester (Death SS) - Sabbath Bloody Sabbath
Tony Demolition Dolan - N.I.B.
Maksymina Kuzianik (ex-Setheist)/Mayara Puertas (Torture Squad) – vocal duet on Killing Yourself To Live
Tony D' Alessio (Banco del Mutuo Soccorso) - Heaven &Hell
Flegias (Necrodeath) – Paranoid
John Gallagher (Raven) - Children Of The Grave
Simone Salvatori (Spiritual Front) - A National Acrobat
Andrea Zanetti (Monumentum) - Hole In The Sky
James Rivera (Helstar) - War Pigs
.
Guitars:
Marty Friedman - Symptom Of The Universe
Filippo Marcheggiani (Banco del Mutuo Soccorso) - acoustic solo Symptom Of The Universe
Mantas (Venom Inc.) - Sabbath Bloody Sabbath
Terence Hobbs (Suffocation) - N.I.B.
Prika Amaral (Nervosa) - Killing Yourself To Live
Ken Andrews (Obituary) - Heaven & Hell
Sonia Nusselder (Crypta/Cobra Spell) – Paranoid
Russ Tippins (Satan) - Children Of The Grave
Attila Voros (Leander Rising/ex-Tyr/Nevermore/Satyricon) - A National Acrobat
Wiley Arnett (Sacred Reich) - Hole In The Sky
James Murphy (Disincarnate/ex-Death/Testament/Obituary) - War Pigs
.
Drums:
Snowy Shaw (Dream Evil/Mercyful Fate/Therion) - Sabbath Bloody Sabbath
Marc Jackson (Acid Reign/Sin Theta/ex-M:Pire of Evil) - War Pigs
Dario Casabona (Schizo) - Hole In The Sky
.
Keyboards:
Freddy Delirio (Death SS) - Sabbath Bloody Sabbath
Heric Fittipaldi (Scenario) - Heaven & Hell