This is my first guide. and iv'e noticed that this build has worked really well for me. but be noted that every build changes depending on the other team. if the other team is ap heavy i usually throw in a wits end. or perhaps a maw of Malmortius.
the runes i chose are good for an ad top opponent. or if you are going jungler Rengar they seem to work really well. the armor pen is very nice when you get three kills while having the bone tooth necklace. cause then you have 25% armor pen. and you really put a hurting on top lane.
these are the masteries i like to use. but everyone has there preferences. i mean there masteries theres not much more i can say about them.
The items i have chosen seem to work very well for me. but this is because i'm going off the idea that they have an ad top ad jungle and ad carry. which happens in most games. but it still works if they have lets say an ap mid and ap top. you just have to swap out something to get some MR. Maw of Malmortius is good. or wits end works fine to. wits end stacks nicely when your at full ferocity and you press q your attack speed is doubled. and you attack extremely fast.
The summoner spells i chose flash and ignite work good for me. i rarely use my flash for a kill because of rengars passive and his ultimate. but it nice to have when the other teams ad carry is out of range from your ult. i mostly use the flash spell when i need to make a quick escape. and i love ignite because it really secures the kills.. other spells that i find useful when are ghost and exhaust. i usually use smite flash for when i go jungle rengar.
Team work try to take down there main threats with your ult. while your team fights the rest. as in going for the ad carry/Ap carry. if you can manage to kill the carry you team shouldn't have a problem winning a fight.
Creeping / Jungling
Jungle Rengar is really easy not the fastest jungler but still pretty fast. he farms really well because of his passive and can heal himself greatly. also he doesn't use mana so it helps out when you can give your mid the blue golem buff. his ganking potential is really good if you have 5 stacks and you use your bola to stun them. he works really well if you go through the lane to gank because then he can jump from bush and throw out lots of damage. also very nice if you can gank bot early. early drag can help drastically. i try to gank lvl 2 because most likely the other team hasnt set there wards yet.