The material for Tactical was written by Miller and arranged with drummer Tim Yeung, with the exception of the two cover versions: Megadeth's "Wake Up Dead" and Malevolent Creation's "Alliance or War".

[6] Death guitarist James Murphy joined the group as a guest musician, performing guitar solos, bass and keyboards on numerous songs on the album, which he also mixed and mastered.

[10] Lyrically, Tactical deals with a number of complex personal and philosophical concepts, which Miller detailed in a track-by-track feature prior to the album's release.

Within the feature, the band's frontman proclaimed that he was "obsessed with mental illness", and noted that at least three tracks on the album featured lyrical references to various mental conditions – "Pyro-Compulsive" is based on "the idea of someone lusting over lighting their house on fire while they're inside";[11] "Dead and Still in Pain" is written about depression and anxiety, in particular "not knowing what to do with yourself or where to turn";[12] and "Under the Autumn Low" references seasonal affective disorder, from which Miller claims he suffers on a regular basis.

[12][13] "Into the Arms of Cruelty", which Miller has claimed is one of his favourite songs on the album, is described as the vocalist's "unrestrained opinion" on child abuse, which he says makes him "fucking sick".