Buff/Rerework Cassiopeia.
Can we just give her a 30% AP ratio increase on her Q? I know this is the Worlds patch and all, but this buff would take you not long at all to implement. Besides, it would be a nice buff for the players who liked playing her as a poke mage without affecting her all in Twin Fang machine gun thing she's got going on now too much.
Hell, Cass has a low pickrate AND a low winrate, and has for a while. Why are you hesitating to buff her, Riot? I highly doubt it would break her.
But, yeah. Cassiopeia Q: 45% AP -> 75% AP. It's very simple. You just have to change the numbers.
That or you could admit the rework was a failure and revert her but like that's going to happen, amiright?

EDIT: Does anyone remember when
was core? Glorious time.