Question: What did Nocturno Culto's bandmate play primarily? 

Context articles: Goatlord (album)
Shatter (EP)
Circle the Wagons
Dark Thrones and Black Flags
Sardonic Wrath
Darkthrone
Fenriz
Ivar Enger
Nocturno Culto
Only Death Is Real

Goatlord is a demo album by Norwegian band Darkthrone, released in 1996.
 The album was re-released by Peaceville Records in 2011, with new artwork approved by the band and a second disc containing commentary from Fenriz and Nocturno Culto.
Shatter is an EP by Swiss extreme metal band Triptykon, released 25 October 2010.
 The EP consists of the bonus track "Shatter" from the Japanese edition of "Eparistera Daimones", as well as other songs from the recording sessions of that album, including a newly mastered version of their demo "Crucifixus".
 Tracks 4 and 5 are live versions of Celtic Frost songs, recorded during Triptykon's headliner performance at the Roadburn Festival in Tilburg, The Netherlands, on 16 April 2010.
 "Dethroned Emperor" features guest lead vocals by Nocturno Culto (Darkthrone, Sarke).
Circle the Wagons is the 14th album by the Norwegian band Darkthrone.
 The album was released on 5 April 2010.
 Fenriz, the band's drummer, described the music as Darkthrone's "own brand of heavy metal/speed metal-punk" and declared it a further shift from their old black metal style.
 About half of the album was written by Fenriz and half by Nocturno Culto.
Dark Thrones and Black Flags is the 13th album by the Norwegian band Darkthrone.
 Released in October 2008, the music largely followed in the style of their previous album, "F.O.A.D." Half of the lyrics and music were written by Nocturno Culto, while the other half were written by Fenriz.
Sardonic Wrath is the 10th album by the Norwegian black metal band, Darkthrone.
 It was released by Moonfog Productions in 2004, and was the band's last album on that record label.
 Although punk influences were already apparent, it would be Darkthrone's last album recorded solely in the black metal style.
 Their subsequent albums featured much stronger punk traits.
 However, Einar Sjursø observed in "Terrorizer" that "even if there is a certain punk "attitude" to the odd riff here and there" it is a case of "the diabolic duo [Fenriz and Nocturno Culto]...simply drawing more influences into the Darkthrone melting pot, turning them into crystalline "Darkthrone" riffs [author's emphasis]".
Darkthrone is a Norwegian heavy metal band.
 It formed in 1986 as a death metal band under the name Black Death.
 In 1991, the band embraced a black metal style influenced by Bathory and Celtic Frost and became one of the leading bands in the Norwegian black metal scene.
 Their first three black metal albums—"A Blaze in the Northern Sky", "Under a Funeral Moon" and "Transilvanian Hunger" (sometimes dubbed the "Unholy Trinity") — are considered the peak of the band's career and to be among the most influential albums in the genre.
 For most of this time, Darkthrone has been a duo of Nocturno Culto and Fenriz, who have sought to remain outside the music mainstream.
 Since 2006, their work has strayed from the traditional black metal style and incorporated more elements of traditional heavy metal, speed metal and punk rock, being likened to Motörhead.
Gylve Fenris Nagell (born 28 November 1971), better known as Fenriz, is a Norwegian musician and politician who is best known as being one half of the metal duo Darkthrone.
 Although primarily a drummer, he has also performed bass, guitar and vocals for Darkthrone and a number of other metal bands.
 Fenriz is known for his refusal to play live, his obsessiveness about music listening, supporting other underground bands and his lack of interest in the mainstream music business in general.
 Fenriz has had three solo projects: the folk metal project Isengard, the dark ambient project Neptune Towers and the doom metal project Red Planet.
Ivar Enger, also known as "Zephyrous", is a guitarist who played for the black metal band Darkthrone.
 He is credited as featuring on the band's first three albums; "Soulside Journey", "A Blaze in the Northern Sky" and "Under a Funeral Moon", as well as the "Goatlord" album; the rehearsal tapes of what was originally intended to be their second album (with later added vocals).
 He is said to have left due to delving into misanthropy , instead of generally leaving, as Darkthrone never had touring stress and he didn't leave prior because of the swift change from death metal to black metal, like other former member Dag Nielsen did.
 The band maintains that Zephyrous went into a forest and never returned.
 However, in a 2006 interview with the German website Voices From The Dark Side, Nocturno Culto claims he still has contact with Zephyrous and would like him to join the band as a guest on a few songs at some point.
Ted Skjellum (born 4 March 1972), also known by the stage names Nocturno Culto, Nocturno or Kveldulv, is a Norwegian musician best known as the vocalist, lead guitarist, and partial bassist (shared with Fenriz) of the influential black metal band Darkthrone.
 He has been with the band since 1988.
 He is also the vocalist of the band Sarke.
 He currently works in Norway as a school teacher, and has a son and a daughter.
 He has also released a documentary film called "The Misanthrope" in which he deals with black metal music and life in Norway.
Only Death Is Real: An Illustrated History of Hellhammer and Early Celtic Frost 1981–1985 is a non-fiction book written by Tom Gabriel Fischer with collaboration of Martin Eric Ain, published through Bazillion Points on March 30, 2010.
 The book features an introduction by Nocturno Culto of Darkthrone and a foreword by author Joel McIver.