For some of these, I imagine a final battle scene in a movie instead of a game. I'll split them up a little: Nexus is more movie-oriented, but I totally see a game coming from one timeline; regardless, characters and battles would likely inspire more rock, modern music for battle scenes. Blades of Allegiance would be 100% an RPG, so the music would likely more fantasy, powerful and instrumental.
"Save Our Souls", Revis is perfect for a group battle for a younger group of heroes: probably my 2nd generation Loa Squad, including: Iris, Jin, Frankie, Azra, Takoda,.
"The Infection", In This Moment or "Something in the Wood", Blue Stahli sorta has that final scene build up to it - or even like a teaser trailer element for a battle scene. I see this for a battle between Pane'xia and Kenna.
"Let You Go", Chase & Status, feat Mali might not be "final battle", but there's definitely a personal element to it - so a fight between allies, someone looking for revenge, or a good guy's gone bad, etc. I see it for Alexis fighting against my other mains: Amira, Torrie, and Adrien.
I love anything by Zack Hemsey, but "Silver Crimson Black" is perfect for Alarick (Silver), Elehah/Kyla (Crimson) and Daina/Lilith (Black).
"Soldiers", Otherwise is definitely last battle material, likely with all my Nexus mains.
"I'm So Sorry", Imagine Dragons is made for Hana, who just wants to destroy everything - so it'd be a boss battle between her and a building. That building never saw it coming.
Nexus 412-MU (which I'd love to see a game based on):
I also see "Vengeance", Zack Hemsey for a scene where the heroes have all lost, but there's still one person left standing. This would be Karina/Riley, hands down.
"Remedy", Seether could totally be for a fight to the death between Anna and Naila. Ironically, they're fighting in a medical facility.
"Bow Down," Lo Pro would be for a very intense, likely death-inducing battle scene. Kenneth is attracted to intense near-death experiences, so this is probably his jam. And he'd probably be fighting everyone in existence.
"Vanguard", Violet Chachki would be 100% perfect for Kenneth and Jayden against the entire police force, and my two main detectives in this game idea; fun fact: it starts with Kenneth doing pole dancing in drag.
"28 Theme", John Murphy would sorta be for a "bad route" ending in the game, where one of the detectives goes seeking out their target, and needs to fight for survival - but is quickly overwhelmed. Sorta a forced failure boss battle.
"Retribution", Blue Stahli between the main detectives (they have no names yet, ahem) against Anna.
"Lightspeed Combat", Blue Stahli for the MD against Ariana and Texa.
"Rebellion Anthem", Blue Stahli or "Rockstar", Blue Stahli for the MD against Azra
Blades of Allegiance (would be a very looooong game):
"Guardians at the Gate", audiomachine could go for either a fantasy game or movie, but I mostly see it for the battle for all my mortal Blades of Allegiance bbys.
"The Calling", Zack Hemsey (because this man is a genius) demands a scene between my protagonist, Rexiluhs, and the big bad, Jahen.
And then the "Kings" (five collective Gods) are forced on to the physical plane, brainwashed into destroying the world. Battles would commence between Rexiluhs and his gathering, and the "Exiles" (the other five Gods stripped off their titles).
"Serenata Immortale", Immediate would be great for Rexiluhs and his band of merry men against the God of Heavens, Skies and Wind: Hy'nazure.
"Ode to Power", Immediate screams a battle against the God of War, Justice and Temptests: Rolustner,
"Carpe Noctem", Mark Petrie for the God of Nature, Beasts and Earth: Vemenyus.
"Rebirth", Hi-Finesse would be for against the God of Love, Family and Fertility: Sorelperess
"Legion", Brand X Music for the God of Sea, Life and Rebirth: Variessro.
Oooookay, I'm done.