Thanks guys for tips and tricks. This is my first "serious" attempt to make a build, so it's far from perfect. Rengar isn't even my main champ, but I like him quite a lot, so I tried to summarize my opinion about him.

I agree the build looks like ****. I don't know how to put icons in there or make it easier to read via better formatting, but I'll try to improve.

I also agree with fact, that most of his damage output comes from abilities, but I didagree with non-crit marks. Main damage goes through Q (especially 1v1) and that can benefit from crit marks unbelievably well... You'll see if you get lucky with enhanced Q crit.

As for the item building - I disagree that Warmog without Atma's is waste of money or space. At least not with Rengar. You end up with like 3k of HP which means Atma will provide you let's say +50 AD (and some armor and crit). It's not bad, but it's not great either. As I already said, I take crits as a bonus (especially nice to get them with Q), but not core stuff. Lack of armor could be achieved with W (or double W) so there's no real need of it too. And building it just to get 50 AD is not that great - you can build Bloodrazor instead etc.

And why do I build Warmog in the first place? It's nice to have more HP and regen and this is HUGE boost to those. Frozen Mallet could be good substitute if they have good runners :-)

Try to use some Icons
You can make them when you write Name of a campion,Item or spell

Voted +

Dont get warmogs, get something like a frozen heart or a last whisper depending on how your doing. Lacks coding and is a wall of text.

Your crit marks could change, since he does most damage with his abilities. He shouldn't be attacking too often on champions unless he has no abilities ready, in which case he should wait in the jungle. Also, a Last Whisper could do some wonders against tanks, if it comes down to it, but Rengar is basically used against carries. Over all good build, and warmogs armor without Atma's Impaler is almost a waste.
Items to consider.
Frozen Mallet
Yommuu's Ghostblade
Atma's Implaer
Last Whisper