Have you ever thought about skins inspired by classical music?
My first pick would be Conductor Fiora. Her weapon would be a baton and this would be her abilities:
Passive - There would be lines of staves with maybe a note or two.
Q - no special
W - Again some staves, which become golden when struck by hard CC and many notes appear on the staves.
E - Her baton glows silver and then golden
R - staves appear around the target, with more notes than on the passive. When the field activates it has four curtain like bows and a big clef in the middle.
Any more ideas for this skinline? My only other idea would be Drum Player Galio, but I think this theme would have potential.