Lissandra suggestion :)
Lissandras task in teamfights is to go all in, cc the whole enemy team and deal some dmg. This is fun but it feels a bit out dated.
So my suggestion is keep her passive like it is and add an additional effect: Lissandras abilities deal increased damage the more enemies they hit. (or maybe just her ult?)
It would fit her gameplay so well and it would actually be very rewarding to go all in and manage to hit the whole enemy team. Also there is enough counterplay to it because the enemy team has to be careful about their positioning.