When writing lyrics he often takes long walks in the Norwegian countryside near his hometown of Bergen for inspiration.
Demonaz and Abbath comprised the core of Immortal in its early years, with an unstable lineup until drummer Horgh joined the band in 1997.
Demonaz played guitar on the albums Diabolical Fullmoon Mysticism, Pure Holocaust, Battles in the North and Blizzard Beasts.
After having surgery to correct his tendinitis in 2013, Demonaz was able to play guitar again and returned to Immortal as a guitarist and vocalist following Abbath's departure in 2015.
Immortal's first album to feature instrumental contributions from Demonaz in 21 years, Northern Chaos Gods, was released on 6 July 2018.