Please don't change Rengar's abilities anymore. His bola was very difficult to use during 6.3, but its a little better now. I'm kind of a Rengar main since the end of season 4, and I understand his kit is frustrating to play against, but lets look at the facts.
-He is an assassin.
-He has a single reliable gap closer, but potentially infinite more if you choose to wander around the wrong part of the jungle or lane by yourself.
-In order to one shot, he needs lots of gold. LOTS. (That's not to say he can't kill you a little slower with a little less, but it won't be instant)
-He is very reliant on enemy mistakes.
-He is highly dependent on map awareness.
Knowing this, he doesn't need to have his abilities changed like the bola. Nerfing numbers is fine. He is a little too strong for the amount of gold you spend. But late game fantasy Rengar should not be touched. He has tons of weakness, and it can be exploited no problem.
Now that we have the whole "don't change his abilities again, we just got used to the last time you 'fixed' him" out of the way, on to Rengar.
I highly recommend this champion in the jungle, top lane, and maybe even a cheesy bot lane (Rengar Shaco is hilarious). He is fairly easy to play and do decently with. However, he is a difficult champion in the sense that he cant just hit q and right click a full team to death at 1000 mph (
). Completely solo carrying a game as Rengar is a combination of making the other team tilt, taking advantage of over-extended enemies, map awareness, and sometimes sheer brute force. Mechanically, he is not that intensive. Once you learn what combos to do when, its muscle memory.
Again, I love playing Rengar. There is something so satisfying about roaring out of a bush and killing things with a big knife and claws. Also, his laugh is quite possibly the best in the game. If you choose to pick up Rengar, I wish you the best of luck in your games, not that you'll need it. Enjoy making the other team's squishies beg for mercy!