Jazz Singer Ryze
I was joking with my brother how Ryze essentially takes out his enemies by swinging his arms going "Zip-zzop, dippy-doo-wop!" when this idea came to me.
His suit looks something like this: https://i.kinja-img.com/gawker-media/image/upload/s--H6SqopmX--/sylfw1ctszrjwwsdxp4i.jpg
He carries a giant instrument case on his back. He scat sings every time he casts a spell. "Zip! Bop! Dippidy-zop!" His ult has him jazz dancing. His dance has him pull out an instrument and start playing a song. His joke could have him start singing rock-and-roll, then he pauses mid-song, saying "Whoops, wrong genre." His taunt could be "C'mon, I know you can swing harder than that!" His recall could have him taking out the instrument on his back, plopping the open case down in front of him, tuning the instrument, then teleporting right before he actually plays the instrument.
He could be tied into the Debonair skin line, with his splash art having him playing in the foreground while Debonairs Galio, Ez, Vi, and the rest are chilling in the background. Maybe have some Mafia skins walking around in the background too.