What is "geasa"

Geasa is a Celtic metal band originating from Dublin, Ireland. Formed by Fergal Purcell and John Kavanagh in 1993 the band combines traditional Celtic music with black metal to form Celtic black metal. They have released one demo album, one EP, and three full-length albums. They came onto the scene in 1994 with the much acclaimed 'Starside' demo. The demo was widely traded in the underground and attributed to the band's later record deal. The demo itself comprises two distinct sounds; from the epic black metal sounding 'Empyrean' and 'Warrior' penned by Purcell to the more Celtic sounding 'Starside' and 'Rite of passage' written mainly by Kavanagh. Indeed it was this black metal sound lost when Purcell quit the band in 1996 that resulted in the band's major and sometimes-lamented change in sound style post Starside.