The Ruby Weapon's theme from the second phase of Cinder Drift.
I guess it's Nael's theme, though :^)

Official Lyrics:
Corvus fortis
Corvus fortis
Corvus fortis ascendit
Superne videt praeteritum
Praesentem et futurum videt
Res evertuntur repente
Ad unum omnes sunt mortui dei
Machinae regnabunt in caelo
Ratio regnabit in terra
Corvum candidum exhilaramus
Ecce extendit trans mundi alas
Vocat lucem rubram excidii
Fulget luce rubrae victoriae
Imperium!
Imperium!
Imperium ave!
Ave imperium!
Ave imperium!
Videte!
Testate adventu fati
Videte!
Testate adventu Dalamud!

Rise of the White Raven [THE PRIMALS] (Ruby Weapon Phase 2)

Not affiliated with Square Enix.
Please buy the OST if you can.

Rise of the White Raven [THE PRIMALS] (Ruby Weapon Phase 2)

FFXIV Music