Mezzadurus (Chris Gamble) - Vocals, Bass (1995–2002) – Mezzadurus was recruited to perform bass and share vocal duties with Proscriptor and Shaftiel for live shows. He appears in all live videos of the band from 1995 - 1997. Mezzadurus currently plays in two bands, Blood Storm, and Goreaphobia.

Lynette Mitchell - Vocals (1993-1995) - Lynette performed some vocals on Barathrum: V.I.T.R.I.O.L. and The Sun of Tiphareth. Her husband engineered ABSU's first two albums.

Rabicante McDonald - Guitar and Bass (1997) - Performed Guitar and Bass for ABSU's cover of Transylvania on the tribute album A Call To Irons: A Tribute To Iron Maiden. He also performed on Proscriptor's solo release "The Serpentine Has Risen"

Bard Algol Eriboas (Josh Cook) - Synthesizer & Effects (1995) - Performed the song "The Great Battle Moving From Ideal To Actual" on the previously unreleased 7" Hallstattian Swords EP (later released on the "Mythological Occult Metal: 1991-2001" compilation). Josh was the sole composer for his band Cernunnos Woods.

Ashmedi (Melechesh) - Vocals and Lyrics on "Tara" and "Absu".

Blasphemer (Mayhem, Ava Inferi, Aura Noir) - Guitar solos on "Absu" and "Abzu".

David Harbour (King Diamond) - Synthesizer, Keyboard and Piano on "Tara" and "Absu".

Nornagest (Enthroned) - Vocals on "Absu".

Vorskaath (Zemial) - Vocals, Brake Disc, Gates, Greek Bell and Vibraslap on "Absu".

Mindwalker (The Firstborn) - Vocal and Ceremonial Tibetan Horn on "Absu".

Michael Harris - Guitar solo on "Absu".

Sir Don Shannon - Bagpipes on "Tara".

Sir Vincent Rossi - Acoustic Guiar and Mandolin on "Tara".

Masthema Mazziqim (Azazel's Torch) - Vocals on "Tara".

Ronnie Trent (10 Kingdoms) - Vocals on "Tara".