It's been awesome to play all these assassins after their updates. A particularly cool feature of Katarina dash is now that you can choose a landing spot.
I've really loved to play Xin ever since I picked him up. He is still one of my favourite champs if only because he is simple and straightforward. That comes at a price though. Having played him for so long, you gradually start to see the downfalls of his kit. Due to his kit being so straightforward, I think he could use something of a update too. For example a similar feature like Kata dash:
By activating E, you could choose a point to land around a selected target, in the shape of a circle, or a half-circle curved side towards you. As for the passive application, it could auto-target the closest. This would open more options to the player and not be completely shut down by a linear skillshot because you cannot do much else than dash straight at your opponent.