|This article is written from the Real Life point of view|
This theme is first played briefly at the beginning of the Brug Mass boss fight in the BOTTLE SHIP Control Room, which switches to a different theme once Commander Adam Malkovich authorizes the use of Missiles. The full song plays in Sector 1 / Biosphere during the dual boss battle against Namihe and Fune in the Subterranean Control Room. Additionally, this theme is used in the battle against Nightmare Unmasked in its room in Sector 2 / Cryosphere, replacing a different theme used in the first battle; however, it does not seem to take any inspiration from Nightmare's original battle theme in Metroid Fusion.
Like many other battle themes in Other M, this theme is evocative of James Horner's score for Aliens. It consists primarily of heavy metallic percussion beats, quietly accompanied by unsettling high-pitched strings and "growling" low brass. It has little (if any) definitive melody, largely serving just to create tension.
This theme can be heard here: