In 1987, Blomberg, alongside Steinar Sverd Johnsen and Marius Vold, formed the avant-garde black metal band Arcturus (initially under the name Mortem), which disbanded in April 2007 and reunited in 2011.

Eventually, he discovered Venom, Celtic Frost, and jazz, inspired by a previous drum teacher.

[4] The first recordings he completed with Mayhem were two songs for a compilation album around 1989, featuring the tracks Carnage and The Freezing Moon.

Following that album, Mayhem encountered lineup difficulties due to the suicide of singer Dead and the departure of Necrobutcher.

In 1995, he joined Immortal as a session drummer during their tour that year,[6] and he also contributed drums to their first official video, Grim and Frostbitten Kingdoms.

The recording and release of Arcturus's debut album Aspera Hiems Symfonia also occurred in this year.

In 1997, Jan Axel began collaborating with Covenant, now known as The Kovenant, for the recording of their second album, Nexus Polaris.

In addition to these collaborations, Jan Axel has made numerous guest and session musician appearances on various releases.

[8] He, however, came to distrust the attitudes he considered "weird": I came to his house: he was all dressed in black, and there was a knife hanging on his belt.

Initially, driven by youthful curiosity and having read various books on occultism that described different rituals, Blomberg soon realized that he was entering a dangerous path: Soon after, we got into everything connected with death, the dark side of life, and Satanism.

And Dead followed in his footsteps.Blomberg served as the session drummer for the Christian black metal band Antestor, contributing to the EP Det tapte liv and subsequently to the album The Forsaken, which also featured vocalist Ann-Mari Edvardsen.

[citation needed] Hellhammer's appearance on the recordings elicited a polarized reception within the metal scene.

"[10] Additionally, Hellhammer stated that no member of the new lineup was a Satanist,[11] and that the "Satanic stuff […] isn't what I feel Mayhem is about today.

"[12] Antestor vocalist Ronny Hansen remarked on Blomberg's contribution: First of all, Jan Axel "Hellhammer" is a total professional.