Bartholomew
Swashbuckler
If anyone plays with audio like I do they know that the same three tracks loop endlessly when going into combat, so I think it would be pretty cool to add combat music specific to what island you are on. Basically just like how every island has its own theme while out of combat, except every island will have its own theme while in combat. Not only will this break the monotony that the music stacks on to loot and Rep farming, but it will also encourage people to revisit the islands to hear what all the combat themes are.