Rengar's rework was not a failure keeping bonetooth was.
Bonetooth ALWAYS breaks rengar since RELEASE.
Bonetooth is far too inconsistent to be balancable since it's completely based on player kills.
This one is far more consistent however due to it, it's binary.
Current one enables direct FULL tank rengar with just 1 AD item.
(And no it's not W that enables it because taking less damage makes the heal really minor for such a long CD and 1.5 seconds is far to reactive for tank rengar to compare when it should be used.)
It really isn't "fun" just WTF factor from 500+ AD and unlike jhin, this kitty can AA constantly. Not to mention bonetooth enables the crit+AS on assassins balance issue.
Now what rengar's bonetooth SHOULD have been replaced with is a kha's evolution mechanic.
This would be far more consistent since it's based off exp something you're sure to get, meaning balancable.
It would be FAR more fun because you can augment skills uniquely per match.(Even when meta skill maxes happen some kha will start augment r for more map pressure, e(rare) if the enemy reacts too well to his assassinations on their ally, w if he needs to add on a bit more cc and waveclear instead of Q.)
It fits his hunter theme because hunters aren't just about taking down prey and showing it off but taking their experienced gained from hunting to further develop their skills.
It will still envision his AvP theme because Predators have been shown to improve tech for use vs aliens.
It COULD still work off player kills, maybe per ulti rank takedown a specific enemy jungle camp or an enemy champion(unique so rank 2/3 can't be same target unless kha) (must do damage in 1.5 seconds of them dying for assist)
Hell to take it a step further killing kha doesn't augment skills until the event starts.(I also say maybe kha has to earn kills every ulti rank excluding rengar until the event starts. Which would tone him down, but my main focus is rengar.)
Now for rengar's base skills:
Q is SO much better than old Q finally addressed AS+Crit's balance issue(sustained damage on assassins eve, shaco and rengar had issues with it, only eve's trademark hate spikes remain QQ).
Now they're MUCH better clear tool. His Q's delay also improves counterplay.
W is a great assassin form of combat healing, I would say it's not comparable to the old but it does such in jungle except for the damage. It also isn't enabling tank rengar because if you take less damage it's harder to judge when to reactively use it and has a lengthy CD making tank get far less value from it.
E, same e as always, now my issue here isn't it being a skillshot but the abuse case of just charging E for leap root is gone/given a counterable window. Why the hell were the changes to force it clunky not removed?
R, change it to bonus damage not a crit. Overall R change, while disputed, was a dramatic improvement. Given proper counterplay, for more power. I would also go so far to say it fits rengar even more theme-wise. He's proud of himself and his skills, yes he's a combat genius, but he feels like the type who wants the thrill of having his prey knows he's coming and slowly near them apart.
Rengar's kha evolution could MAYBE:
Grant first part of Q full AoE(not second)
W maybe increased % healing?
E maybe 2 charges?
Ulti- Empowered could mark targets 500 units near your marked target and they take 50% of the marked bonus damage. (Basically this empower would reveal more units near your closest and while your main mark is still juicier you'd still get slight damage on others if you can't find the right angle)
Remember this is WITHOUT bonetooth, I do believe rengar w/o it is great, but I still question why even if assassin patch aren't major reworks what type of idea it was to keep bonetooth.
Also some VFX and SFV could be improved.
Rengar's old q being crit animation, rengar's old W lines are few things asked for.