Blackmass was formed in 2001, when the infernal warrior Lord Aeshma grew dissatisfied with a black metal band he was in because of creative differences. Thus, in October, he departed, ready to unleash his own project featuring extreme techniques, blasphemy, and aggressive speeds, transforming his dark ideals into songs with truthful satanic essence. It then came to be that in the year 2002, after many grueling auditions, Magus Dux Adramelech joined the horde as vocalist in January and became a permanent member in March. Thenceforward the unholy duo Aeshma/Adramelech turned out to be the grease that let the infernal gears of Blackmass spin well. With few rehearsals, Blackmass wrote songs to record their first self financed album, however the duo was without a drummer. In response to this, Magus Dux Adramelech decided to record the drums even without having any prior experience behind a kit.

In May, the group entered Veronese Studio to record their debut demo-cd "Diabolical Ritual" which would feature Lord Aeshma recording guitars and bass, and Magus Dux Adramelech recording the vocals, drums, and keyboards. This one have five tracks: An intro, a slow song "Ravenous Demonium", and three fast songs. The title track would stand out, however, and this was the one that would guide Blackmass' sonority. The horde would appear in several magazines with prominence. The record had a positive response in the Brazillian underground scene, including a proposal to be featured in a compilation by Black Hole Magazine. The began to be respected as true professionals in the scene, and started truly reaping the rewards for their hard work. New member Verberibus Necare was added as the permanent skinsman in 2003, which would see Magus Dux Adramelech taking on bassist and lead vocal duties. Eventually Blackmass' line-up was complete, and it brought a new level of aggressiveness, technicality, and speed. Blackmass now can write faster, more satanic songs than on the first album. Then in August, the band would return to Veronese Studios to record an EP entitled "Episcolum, Servo Servorum Santii". This EP would feature the track that was considered by many to be Blackmass' masterpiece, "I Call Upon Thee". In December, along with being featured in additional magazines and publications, Blackmass would go on to be featured in an Extreme Underground compilation with a song called "Daemonarchetypes".

2004 began with Blackmass playing a multitude of live shows around Brazil, while at the same time concentrating on new material to show the Brazillian black metal scene an album never seen before. In June they would work up enough tracks to record their first full length album, and would begin shopping around for a record label. Their first record deal was with Black Metal Mafia from So Paulo. The relationship with this label would be ended soon after because of a breach of the contract. The next good record label offer came in 2005 from Blasphemy Productions. BlackMass, now armed with this new backing would enter Poly Studios to record their most aggressive, hyper, and technical album yet, "Gloria Diaboli". This album would feature songs such as "Necrologies", the technical "Xes Lehahiah Plegas", "Infernal Horned God" and "Alae Nocturnae", which was sang in Latin. They also invested much more effort into their album artwork. Gloria Diaboli was released in Brazil on December 20th through Blasphemy Productions. The album was also released on Sinister sounds in April of 2006.

The ultimate payoff for the band's tumultuous efforts came in 2007, with Pennsylvania based Open Grave Records taking an interest in and signing them on to record their newest piece of blasphemy scheduled to be released in December called "Nemesis".