Hello everyone this is my second guide! People have been saying how amazing my Rengar game is... I use this build every time basically carrying my team :D I hope you like this guide.
TBH: Got a penta kill with him :)

Q: only receives the attack speed buff upon empowered use, which is a good enough change in that spamming your Q no longer allows for automatic CSing AND harassing at the same time, now you've gotta make a choice, and that's great- free lane phases are never fun to go against. It makes it less of an auto-win when pushing down turrets/split-pushing which is another plus regarding the approach to his 'toxic' gameplay, BUT removing the ability to Q turrets entirely really hurts Rengar in that he now... doesn't really do much to turrets at all. The clunkiness which has already been identified and is being fixed by Riot in the next patch can be ignored as they've addressed it and given an official response. Despite all of this, the nerf to his empowered Q early game is the only thing that truly bothers me about the new Q. It's very underwhelming, and definitely shows during lane phase. Rengar's already low base stats aren't done any favors by this change, and he now gets zoned freely by lots of top laners. The 10% extra AD and -2 seconds on the Q CD is great, but I'm not so sure about Rengar's ability to keep up in lane against most of the cast after one-two optimal trades executed by both parties (Renekton was tough enough to go against pre-nerf!)
W: I like the way this ability was dealt with in that it rewards you for diving in on more enemies, BUT removing the scaling cooldown now makes it extremely underwhelming when you level it up. There's almost no reason to do so before the other two abilities, as the utility of a tiny bit of extra armor/mr isn't really doing much, and the empowered version scales off of Rengar's actual level and not his ability level. You can triple W now from using your ult though, which is pretty neat as AP Rengar lol.
E: I like the skillshot approach, as well as making the range enormous, but again the removal of scaling cooldowns is hurting it for me when deciding what to level. It's almost like Riot wants Q to be the mandatory skill to max first now. Some people complain the skillshot is too slow but I mean... it's a skillshot for a reason! Learn to land it! Ult lets you triple E now which is a 3.5 second snare, AND at 18 it's an enormous nuke (930 + 2.1AD) so late game it seems like opening up and using triple E will be the best way to nuke squishies. During lane though... E has kind of taken a huge beatdown in that you can't really harass with it anymore if they stand behind creeps, and with how empowered abilities were nerfed down as well Rengar probably won't be able to hang with anyone aside from the weakest toplaners :( I'm torn on this overall change, BUT it's probably for the best as E when maxed had no counterplay, and was almost a free kill in a lot of scenarios when receiving a gank. During lane E has been overall nerfed, but for ganks/poking it's received a huge buff (3.5 seconds of almost unavoidable CC is pretty ridiculous).
R: I both like and dislike these changes, the ! indicator is extremely annoying when playing Rengar, (and hilarious to be on the receiving end of) but the way the movespeed works as well as the ferocity building up AFTER leaving stealth is awesome, it allows for much more choice on Rengar for 'optimal' gameplay, instead of pre-4.5 where Rengar players were absolutely FORCED to triple Q in order to get the most out of their ult. Now, you can triple Q, W, E, or any combination of the 3, depending upon what your team needs, and choice is key when taking into account good character design.

On every wall of his den, the trophy hunter Rengar mounts the heads, horns, claws, and fangs of the most lethal creatures in Valoran. Though his collection is extensive, he remains unsatisfied, tirelessly seeking greater game. He takes time with every kill, studying his prey, learning, and preparing himself for the next encounter with the one monster he never managed to defeat.

Rengar never knew his real parents, but was raised by a human who was revered as a legendary hunter. He was an ideal pupil, intently absorbing the lessons of his father, and improving them with his uncanny feral instincts. Before his mane had fully grown, Rengar set off on his own and claimed a wide territory for himself. Along its perimeter, he mounted the skulls of his slain prey - a warning to would-be aggressors. He thought undisputed reign of a region would fulfill him, but instead, he grew restless. No beasts in his domain proved challenging prey, and without formidable adversaries to push his limits, Rengar's spirit waned. He feared that no worthwhile game remained, that he would never again feel the thrill of the hunt. Just when things seemed their bleakest, he encountered the monster. It was a disturbing, alien thing, distinctly out of place in his world. It bore huge scything claws and devoured any animal that strayed across its path. Overzealous at the prospect of a challenge, Rengar ambushed the monster in haste. It far outclassed anything he'd hunted before. Their fight was savage, and each suffered crippling wounds. Rengar lost an eye, but the most grievous blow was to his pride. He had never before failed to make the kill. Worse yet, the severity of his injuries forced him to retreat. Over the following days, he hovered on the threshold between life and death. He was wracked with pain, but beneath it, he felt a glimmer of joy. The hunt was on. If such powerful beings existed in the world, he would find them, and stack their heads high. The monster, however, was a kill he wanted to savor. On his den's largest wall, he reserves a space for the beast's head, a trophy he swears will one day be the centerpiece of his collection.

''Prey on the weak and you will survive, prey on the strong and you will live.''
-- Rengar

My Jungle route I take with Rengar includes:

Top Side: Golems --> Red Buff --> Smite Crugs --> Go "B" and get jungle Item(Magus) --> Blue Buff --> Wolves --> Scuttle --> gank mid or bot --> Gromp --> Blue Buff --> wolves --> ETC.

Bot Side: Golems --> Red Buff --> Go straight to enemy red; ward -->Take enemy Golems, by the time you are done they should be a quarter health and EZ kill :D --> Gank mid or top --> scuttle -->ETC.