How could Rengar be changed to make him healthy?

Cuz right now, he is a very sick kitty. If you're a squishy, and you're walking next to an unwarded bush, you better hope that isn't in there, or he will insta-delete you with a hop Q. Meanwhile Riot nerf vision capabilities.

It gets to a point where you need to approach the bush to ward it, and hope that there is no Cat-Bear in wait. Risk death or have no vision? Tough choice. Farsights don't even remotely pose a solution.

He also his ult. 70 sec cooldown at level 3 with no cdr/runes.

Rengar has always been meandering between been gutted and being overpowered. Riot find it impossible to balance him. I personally preferred him before he was reverted, when he had his 'new Q' - didn't seem to have quite the same tendency of being so strong.

He would still be strong, but way more healthy, if they turned his main damage source into some kind of stacking mechanic. For example, make it so he can reactivate Q after 1.5 secs or so, and if he hits you with both Q, you take significant damage. Like, as if he is opening a slice in your body then eviscerating your guts with the second hit. :)

Being an assassin obviously he's gonna be bursty, but I don't see why he should jump on you and delete you before you even see him, if he has a bush or ult at his disposal. Like people always say Zhonyas is a good answer, well I'm sure it can be - but not everyone has a 0.05 sec reaction time to hit the button in the fraction of time between him hopping out of a bush and deleting you.