All battle, battle adjacent, and battle intro themes from Octopath Traveler, Octopath Traveler II, and Octopath CotC.
This is currently a complete playlist at 90 songs.

All Octopath Traveler Battle Themes

Octopath Traveler: Champions of the Continent OST

OCTOPATH TRAVELER  Champions Of The Continent –Main Theme–

Herminia, The Covetous Witch

Tytos, The Hero

Auguste, The Playwright

Guided Travelers

Decisive Battle II –Champions Of The Tourney–

OCTOPATH TRAVELER Original Soundtrack

8. Octopath Traveler OST - Tension

11. Octopath Traveler OST - Battle I

24. Octopath Traveler OST - Decisive Battle I

1. Octopath Traveler OST - Battle II

1. Octopath Traveler OST - Battle III

Decisive Battle II –Champions Of The Tourney–

Michael Danielson