2018
Steve Ramsey (Satan)
Remmel (Steve 'N' Seagulls)
Elias Soriano (Nonpoint)
Mark Jansen (Epica, MaYaN)
Jason Hartless
Jukka Pelkonen (Omnium Gatherum)
Lee Harrison (Monstrosity, Terrorizer)
Bob Bagchus (Siege of Power, ex Asphyx)
Kai Bigler (Parasite Inc)
Dianne van Giersbergen (Ex Libris)
Jon Bodan (Halcyon Way)
Mat Sinner (Primal Fear)
Canan Rosen (Riot Grrrls)
Robert Berry (3.2)
Parker Yowell (Seas of Malice, Skin The Lamb, session musician)
Frédéric Leclercq (Sinsaenum, Dragonforce)
Doro
Simone Simons (Epica)
Steffen Kummerer (Obscura, Thulcandra)
Nick Van Dyk (Redemption)
Johan The Blacksmith (Grimner)
M.S. (Harakiri For The Sky)
Tommy Karevik (Kamelot, Seventh Wonder)
Andi Schnitzer (Kissin' Dynamite)
Marco Minnemann
Diamante
Justin Tevtan (Journal)
Tyrant
Glass Lungs
Devin Townsend
Christer Andersson (Tad Morose)
Ray Alder (Fates Warning)
Ronni Le Tekro (TNT)
Jutta Weinhold (Velvet Viper)
Bjorn "Speed" Strid (Soilwork, The Night Flight Orchestra)
Richard Henshall (Haken, Nova Collective)
Peavy Wagner (Rage, Refuge)
Matt Harvey (Gruesome)
Fernanda Lira (Nervosa)
Brandon Kellum (American Standards)
Alien Weaponry
Markus Steffen (Subsignal)
Conan (Exmortus)
Adrian Erlandsson (At The Gates, The Haunted, The Lurking Fear)
Mat Madiro (From Ashes to New, ex-Trivium)
Carmen Elise Espænes (Midnattsol)
Tony Hernando (Lords of Black)
Space Elevator
Jarrett Pritchard (Producer, Live Engineer, Tour Manager)
Jeff Friedl (A Perfect Circle, The Beta Machine)
Nylock (Witch Casket)
Jonatan La Rocca Ramm (Graveyard)
Gus G
Linnea Vikstrom (QFT, Therion)
Follow The Cipher
Valhalla Lights
Tomi Koivusaari (Amorphis)
Ted Leonard (Spock's Beard)
Irini Alexa (Frequency Drift)
Arya Goggin (Skindred)
Chris Naughton (Winterfylleth)
Corky Laing
Alex Alereza (Nekrogoblikon)
Niklas Sandin (Lik, Katatonia)
Antti Kokko (Kalmah)
Screaming Beast
Gill Montgomery (The Amorettes)
J-F Dagenais (Kataklysm)
Frank Healy (Memoriam)
Tommy Rogers (Between The Buried And Me)
Raphael Bittencourt (Angra)
Dino Jelusic (Animal Drive)
Jeff Blanchard (Eyes of the Sun)
Mike Garrow (Savage Hands)
Dobber Beverly (Oceans of Slumber, Insect Warfare)
Doug Alley & Jaco Lidito (Mile Marker Zero)
Alex Veale (Tax The Heat)
Brody Uttley (Rivers Of Nihil)
Troy Donockley (Auri, Nightwish)
Howard Jones (Light The Torch, ex Devil You Know, ex Killswitch Engage)
Stefan Schmidt (Hevatar, van Cantro)
Chris Morley (Cold Kingdom)
Marko Tervonen (The Crown)
Chris Georgiadis (Turbowolf)
Colin Young (Twitching Tongues)
Alan Averill (Primordial)
Niclas Engelin (In Flames, We Sell The Dead)
Al Joseph (Hyvmine)
Zack Zalon (Into The Great Divide)
Alessandro Conti (Lione-Conti, Luca Turilli's Rhapsody, Trick or Treat)
Joey Gonzalez (Philip H Anselmo And The Illegals, Warbeast, Superjoint)
Jan Hoffmann (Long Distance Calling)
Heidevolk
Christofer Johnsson (Therion)
Ivar Bjornson (Enslaved)
Neil Starr & Tyla Campbell (Phil Campbell and The Bastard Sons)
Alexander Bachlund (Letters From The Colony)
Michael Schenker (UFO, ex- Scorpions, Michael Schenker Fest)
Summoning
Mike LePond (Silent Assassins, Symphony X)
Lips (Anvil)
Dan Swano