Ideas to improve my flicker strike slayer

Hi guys. It's first time I tried to create my own build (meaning that I didn't follow any guide) and I tried flicker strike slayer.
I'm kinda satisfied cos clear is amazing, survi is decent but it lacks single target dps, POB is showing ~9M if I set everything correctly.

https://pobb.in/HtfLE1mD3u20

Currently I have ~200div to invest but I need some ideas what should I improve first from some more experienced players :)