Feindflug has carved out a name for itself with an aggressive, synth-based industrial voice. Hirnschlacht continues Feindflug's established sound of unrelenting synths and sirens that is part of a hard electro tradition that may include acts such as :wumpscut or I, Parasite, but is distinctly separate from — and noisier than — them. Hirnschlacht is not a surprising release. The usual fare of screeching synths, the odd guitar, and military beats blend with raid sirens and a marching percussion that continues to dominate the sound. There is no argument that Feindflug's sound has always been unique — they do one dark thing and they do it extremely well. There may not be anything that quite rivals the harsh sonic whirlwind that was "Stukas Im Visier," but Hirnschlacht has its own share of memorable tracks. "Kalte Unschulde" delivers a punishing noise beat through a wall of chords, while "Blutorgel" employs the forked barb of a driven rhythm against the sharp, bright synths that feature throughout the release. In fact, each track's construction differs slightly. The outcomes are consistent — each is a barely harnessed movement, a relentless and harsh energy that does not give in to dancefloor convention. Hirnschlacht sees Feindflug's sound drift toward a new harshness that favors using contrasts (such as the air-raid synths against the undercurrent noise rhythms) more than throwing extra raw noise into the mix. The tensions achieved are familiar from previous releases, but the methods are slowly on the move as Feindflug continues to grow into its sound. Sometimes the expected thing is enough, and Feindflug proves its incredible talent by progressing its unique, dark vision without growing tired or outdated. Hirnschlacht is recommended for any fan of industrial electro who is interested in hearing how one act's sound can help define a dark corner of the genre.