Every pirate crew needs a musician.
This is meant to be a support fighting style (like sniper, doctor and art of weather) and has mechanics akin to art of weather and doctor, as it's meant to buff your allies and debuff enemies. Obviously based on Brook, who has been shown capable of altering other people's emotions and attitudes through his musical skills.
First quest should be something like acquiring an instrument, like a violin or guitar that could be either crafted or obtained with a trader. It would unlock 3 moves, each corresponding to a different sound, similar to Art of Weather's heat, cool and electric balls. By combining these 3 sounds, you can use the rest of the moves (passive's like AoW's tempos), which would be unlocked through different quests, like other fighting styles.
1st Combination - Strengthening Melody: Buffs all nearby allies with a little extra strength and resistance for 10 seconds or so.
2nd Combination - Weakening Melody: Sends out a wave (similar to Goe Goe's or Noro Noro's but with music notes) that debuffs enemies with weakness and slowness for a couple of seconds.
3rd Combination - Sleeping Melody (Nemuriuta Flanc in the anime): Sends out a wave (just like weakening melody) and anyone caught in the wave would fall asleep for a couple of seconds, excluding allies.
4th Combination - Illusory Melody: Sends out a wave (just like weakening melody) that covers the enemy's screen in musical notes, effectively blinding them for a couple of seconds. If used on an NPC, they will move around in circles. Won't affect allies.
5th Combination - Hypnotic Melody: Sends out a wave (just like weakening melody) that temporarily enables friendly fire for whoever was affected, effectively allowing them to damage their allies during a fight. If used on an NPC, they will immediately target the nearest entity, wether an ally or not. Won't affect your own allies. (really useful in team fights against people with massive AOE attacks) might be hard to implement due to how factions work, idk
This fighting style might not be able to deal any damage on it's own, but it's various support-like abilities allow it to be useful when used in combination with other people.
suggestions would be appreciated