Octarmaments is an electric song which features a lot of sound effects at the beginning, but later on, guitar rhythms are added. At roughly fifty seconds, there is a guitar rhythm buildup with claps, electronic effects and distorted vocals. The track contains an interpolation of the Hero Mode - Onward! jingle, at first a chopped and distorted guitar cover, and later halfway during the guitar rhythm buildup where it is fashioned out of the signature Octarian "burp" effects and is continuously repeated until the buildup ends. Around 25 seconds later, the song repeats. It replaces the role of Octoweaponry from Splatoon and plays during the third and final phase of any fight with an Octoboss. It stops playing once the boss is defeated and the defeat cutscene starts playing, and the rest of the level has no music until the player retrieves the Zapfish. In the Octo Expansion, the song plays in stations with Sanitized Octoboss battles. It can also be heard in Squid Beatz 2, with a maximum score of 145 and 371 in Normal and Hard modes, respectively.
Octarmaments (Phase 1)
This is a very sparse version that leaves just the main instrumental, without the guitars, and most electronic effects. It lacks most of the pauses in the main track, and the guitar rhythm, although it keeps the Hero Mode - Onward! melody interpolation. It plays during the first phase of boss fights until the player damages the boss enough and advances to phase 2 when it switches to the "Phase 2" version.
Octarmaments (Phase 2)
The same as the "Phase 1" version, but now with the guitar line and Hero Mode - Onward! interpolation added. The brief pauses and guitar buildup is added, yet it lacks the vocals and electronic effects. It plays during the second phase of boss fights until the player damages the boss enough and advances to phase 3 when it switches to the "Phase 3" version, which is the version featured in Squid Beatz 2.
Octarmaments (Splatune 2)
In Splatune 2, a medley of the three versions is included instead. The "Phase 1" version is played until 1:15 when it switches to the "Phase 2" version. This plays until 2:30 when it switches to the standard variant for the rest of the song.
This is a loop of the first few seconds of the Phase 1 version, but it's so muffled that the beat can barely be heard. It's also more echoey, making it sound like it's being played from a distance. It plays when the camera is near a Boss Kettle, excluding the kettle for Bomb Rush Blush.
- This track is one of the only two new songs heard in Splatoon 2 by Turquoise October along with Octo Canyon that do not feature any voice samples from Callie.
- One full loop of the Phase 3 version has a total of 27 Hero Mode - Onward! motifs.