In his book Mean Deviation: Four Decades of Progressive Heavy Metal, Jeff Wagner wrote that Grand Declaration of War features "a variety of vocal shadings to match the multi-layered music", between "A Time to Die", described by Wagner as "one minute and forty-eight seconds of black calculus", "A Bloodsword and a Colder Sun" offering "squishy electronic groove, so close to trip-hop that it instantly became the album's most controversial track" and the "mesmerizing ten-minute sprawling landscape of doom" "Completion in Science of Agony". The album's "sonic clarity" was "a complete 180-degree turn" from the band's early "scuzzy 'necro' approach". Parts of the black metal scene had hoped Mayhem would not reform after the murder of the original guitarist Øystein "Euronymous" Aarseth as "that would not be right", or at least were "rather sceptical when it was known that t [sic] MAYHEM should go on even without Dead or Euronymous". Many longtime Mayhem fans despised Blasphemer because "he wasn't Aarseth". Jeff Wagner calls Grand Declaration of War "Mayhem's own Into the Pandemonium, an album that had perverted and turned inside out the black metal genre as Celtic Frost's [Into the] Pandemonium had done to thrash metal". Alex Henderson of Allmusic stated that the band "has outdone itself with the epic Grand Declaration of War, which could arguably be described as black metal's equivalent of Queensryche's Operation: Mindcrime".