Satanicum Tenebrae was an obscure Dark Ambient project by Lord Meyna'ch (Willy Roussel), leader and mastermind of Mütiilation. (He has also been member of Hell Militia, Malicious Secrets, Gestapo 666).
Satanicum Tenebrae was part of the Black Metal underground French group Les Légions Noires (the Black Legions) along with Vlad Tepes, Belketre, Torgeist, Black Murder and many other bands. Satanicum Tenebrae released 3 demos:
Til Helvete (1994)
Voices of the Dark Call Me to Suffer (1994)
Seul (1995)

Read more about Satanicum Tenebrae on Last.fm.