ABOreSSs

aBOreSSs (called on the JASRAC database) is Disc 3, Track 8 on the XenobladeX Original Soundtrack. It is split into two parts: the first plays from the start until 2:56, and the second plays from then until the end. The first part is a remix of no4=D91M, and the second is a remix of no8=UN↑口and巨DIE.

The first part plays as the battle music for the in  (for the second phase of the battle), and the second part plays as the battle music for the  in  (for the first phase of the battle).

Etymology
Separating out the lowercase letters from the uppercase in the title gives 'ares' and 'BOSS', indicating that this plays as the boss music for the Prog Ares. This also aligns with the JASRAC version of the title.