To me it feels like one of those abilities you just have to mindlessly spam nonstop during a battle instead of thinking carefully of when, how and _where_ to use it. I can understand some of these abilities being present on older champions but they shouldn't be added to new champions kits, imo.
I think the missiles should be incorporated into her passive plasma/execute stacks instead, so that when you gain that final plasma/execute stack, it will fire missiles at the target(s), this gives the passive execute, which is very strong, some counter-play and reaction time. Also the missiles do look graphically beautiful so I would like to keep them in some shape or form.
This would also make her passive more unique and less Vayne/Gnar-esque.
For her Q they should make up a brand new, interesting and interactive ability instead. One that highlights your skill expression.
OR you could make the ability target ground in an area, and fire missiles based upon how many are in that area, idk, but I think something needs to be done.