During the writing and recording process, the band experimented with first-person narratives, and expanded upon their sound with the introduction of cabaret, country, flamenco, and show tune influences.

[2][3] The band entered the studio with a "preliminary tracklist" for the album in mind: "[It] allowed us to give more space for the transition and general shape of the record, to help each song complement each other, rather than just feeling random or anything like that.

The first week of May the band posted teaser clips and a Tetris-like browser game, featuring a MIDI version of their song "Welcome to Hell".

[13] Selected vinyl pre-orders of Hellfire came with flexi discs of several of the band's tracks throughout their career, all recorded live at Electrical Audio by Steve Albini in November 2021.

[3] Writing for The Line of Best Fit, Kyle Kohner found Hellfire to be Black Midi at "their most devilish and maniacal", sounding "miraculously and hideously new, proving their aversion to any mindless repetition".

[21] Comparing the album to the band's previous work, Paul Simpson at AllMusic claimed that, "While their 2019 debut, Schlagenheim, was an overloaded, volatile mixture of post-punk and math rock, somewhat resembling a no wave band who grew up watching too much Ren & Stimpy, 2021's Cavalcade found the group exploring a lushly orchestrated avant-prog sound, switching between spiky, angular workouts and softer, more patient compositions.

Lead vocalist Geordie Greep sounds more like a delirious carnival barker than before, and the music brings to mind Mr. Bungle and Fred Frith more so than the King Crimson-isms of Black Midi's past work.