He later joined a jazz fusion ensemble called the Ra Notra Sextet that was writing and performing music similar to Chick Corea or The Mahavishnu Orchestra.

[citation needed] In 1977, Hasselvander joined forces with Bobby Liebling and started a new and serious working version of heavy metal doom band, Pentagram.

In 1981, Hasselvander once again joined forces with The Boyz to release the album Bustin' Out, followed by a Falls Church, Virginia show with Ritchie Blackmore's Rainbow.

[4] Hasselvander moved to New York and recorded the albums Devil Childe[5] and Phantom Lord[6] with former Virgin Steele guitarist Jack Starr.

Only one studio demo and one live recording exists of this line-up including players from Blue Cheer, Cactus, The Plasmatics and The Rods.

In September 1987, Hasselvander made a cameo appearance on Pentagram's second album, Day of Reckoning, filling in on the song "Burning Saviour".

A video from this tour was made into an on-the-road "rock-umentary" entitled Electro Shock Therapy, which featured very revealing moments with Mr. Hasselvander in his natural habitat.

In 1993, Hasselvander was asked to play on a reunion album for Pentagram called Be Forewarned for London-based Peaceville Records, after re-recording the drums for Day of Reckoning to be released on CD.

[2] Soon after, Hasselvander and Victor Griffin were asked to fill in on guitar and drums for British doom band Cathedral who were supporting Black Sabbath on a spring 1994 tour of Europe for their Cross Purposes album.

Hasselvander played many one-off shows with Raven in 2003 with Mark Gallagher sporting a leg cast from an injury sustained in a near death work accident in 2002.

One such gig was marred by an appearance of British rock vocalist Tony Mills, who rushed the stage and declared that he had a contract with the Gallaghers to become the next lead singer of Raven.

[12] In June 2009, Hasselvander and Raven performed two nights in Japan in support of the band's new album Walk Through Fire (2009, King Records).