Riot you made a little mistake. Complexity VS Overloaded kits.
For the recent assassin rework you reworked the kitty of league Rengar. When reworking Rengar part of the thing that you wanted to do with him was to add more obvious or better counter play towards him but instead you just ended up giving him an overloaded kit when attempting to try to give the kitty some options to out play some of the counterplay. The problem with Rengar now is that it's so easy to outplay the counterplay that it just ends up making the kitty have a overloaded kit and not a one with defined
counterplay potential. Another example of a champion with an overloaded kit is Yasuo but the difference is that Yasuo has complexity and actual weaknesses that could get him fucked with one wrong click of the mouse or bad positioning. With Rengar you added CC removal which does not only remove lots of his weaknesses but also makes him low risk and extremely high reward rendering any of the enemies carries useless.
For Rengar as of now you may just nerf his stats and scaling (which will make him shit tier due to him being completely reliant on it now) but you may want to reconsider the way in which you reworked him and look for other solutions to how Rengar will be played. For example if you go onto the RengarMains reddit page you can see that many Mains of Rengar want the complexity and the satisfaction of pulling off his combo to instakill squishies back instead of the R>Q>Spam buttons> Auto "combo" he has now.