Impossible to counterplay? Pls explain

Just played a game against an enemy Rengar.

https://imgur.com/K9u0PCn

There are a couple things about this that aren't okay:

A) Rengar did 1600 dmg in less than 1 second.

B) He tower dove me and there was nothing I could do about it because he was INVISIBLE until he jumped me. So, it didn't even matter that I was under turret.

C) He did almost 900 dmg in just 1 auto attack.

D) He did 300 dmg from nothing???? Pls explain. What even is this?? Why does it exist?

How is anyone supposed to stop this from happening? Even under your own turret where invisible enemies should be VISIBLE? How can I stop him when he can kill me in less time than it takes to blink an eye? I didn't even have enough time to react, let alone fight back.

EDIT: Should I also mention that there were many times where we would all stick together as a group, knowing full well that when Rengar ulted he was either going to go for me ( the ADC ) or orianna ( the mid laner ) .76 seconds isn't enough time for any human to react and completely stop a Rengar from murdering someone that only has 1400 HP. Even if we would be able to kill him easily after the fact, he managed to kill one of the carries every single time despite our best efforts.