Piano can work in action and combat, but it's best primarily where there's a strong emotional undertone to the fight that's ensuing.
I mean... you ever want a boss fight that you just don't WANT to win, because it's breaking your heart...
Vector to the Heavens Just Piano:
Vector the the Heavens, Piano Piano is great. Rhytms, Arps, Strings, Melodies etc. Just by one dude. All Larian needs to do is to pick the "voices" whatever those were called.