Early Game If the lane is passive, buy Sprint Boots first item and get Ava 2nd and put 1 point in Ava, go get boxes.
Mid Game One Shot Combo: Cat to find someone Leaping Slash -> Arctic Blast -> Gloom Bombs -> Quick Melee if needed -> Return to Shadows. This should do 60%-80% of most enemies at this point of the game.
Late Game Scourge + Escalating Exposure if needing to be useful in teamfights