The two build above should be properly chosen according to the enemy team you are facing against. The first build focuses on countering a lot more ad on the enemy team. The second build focuses on countering more ap on the enemy team. *PLEASE CHOOSE THE BUILD THAT BEST SUITS YOUR NEEDS*

Rengar is a predator of the wilds using brush to his advantage can greatly put you ahead of your enemies. One of the most important things about Rengar is how you decide to use his Ferocity. This decision has to be appropriate for the situation your in. Using our ferocity on your q will grant you bonus attack damage and greatly injure your foe. If you are in need of some health then the best choice is to use your ferocity on your w. If you are not sure if the kill is gaurenteed then your best bet is to use it on e.

Rengar is built as a tanky dps (damage per second) to get the most out of this then there are two rune combinations I have found to be very useful on him.
1: You can either build full attack damage to maximize your early, mid and late game damage.
2: Instead of going full ad swap out the three ad quintesences and put in flat health to give you bonus health.

Masteries are pretty basic anything to make you have more health or health regen is always good, and anything that increases your attack damage. Try and avoid crit chance or crit damage because Rengar is a brutal fighter not a ranged ad carry.

Rengar can use a wide variety of items to assist him in either taking down champions or tanking for the team. Your optimal build should include a bit of both. The first item you want to get as a laning Rengar will be a Dorans Blade. If you are jungling then the typical cloth armour and five health potions. When laning with Rengar you should try and counter pick your boots. if the lane has more ap get merc treads, if it has more ad get ninja tabi, if you are undecided try and look at the entire enemy team and then adjust accordingly. If you are jungling Rengar the personally I found getting Wriggles Lantern is one of the best decisions you can make! Wriggles lantern can help you deal great early game damage and provides you with a good amount of armour, also you can use it to constantly ward. This is especially helpful if you are solo top. From here go for a Bone Tooth Necklace, this items is specifically made for Rengar it can prove to be a very good item mid and late game. If you aren't doing so well and not getting that many kills then try and go for Maw Of Malmortius. Your last four items can be any of the following: Trinity Force, Blood Thirster, Frozen Mallet, Guardian Angel, Maw Of Malmortius, Bone Tooth Necklace. *IMPORTANT* Bone Tooth Necklace can fit anywhere in the build by swapping out any item! (Expect for Trinity Force!). If you feel that Wriggles Lantern is just not the item for you then I suggest you swap it out for Maw Of Malamortis.

Rengars skills can both be very useful in a team fight and can also burst down any champion 1v1.
Rengar has to get the most damage possible early game no matter if your jungling or if your laning. First and foremost you need to get your q this will help you no matter what the situation. Then take a small amount of time to address your needs if you are low on health then the best option would be to get w if you think you can manage then get e. The first ability you want to max if of course your main damage output q. Then if you have plenty of kills you should consider maxing w next. If your having a harder time nailing those kills then get e.

Rengar has some fascinating combos what I found while playing him is that using your ferocity is the best advantage you have over your opponents. When in lane try and do the following: Since Rengar doesn't use any mana you can go ahead and spam you abilities but don't get to hasty. What you want to do is when the minions wave comes try and use as many skills as you can to build FOUR ferocity, not five FOUR. While trying to build this ferocity see of you can harass your enemies. When you have reached FOUR ferocity head into the brush from there wait for an enemy to get close enough so you can use your passive to jump to them. Before you jump make sure you press q, when you have jumped out at your enemy hit them with q and then this will grant you FIVE ferocity once you reach FIVE ferocity all of your abilities go on a 1 second cool down and then quickly strike your enemy again with q. But wait if when you jump to your enemy and they start to run away and you aren't in range for another q throw your e at them so you can catch up and start attacking them.

Rengar is a very highly efficient farmer. Instead of staying in lane and just waiting around to last hit, in your enemies line of sight and spells, stay in the brush. Rengar always leaps at his target enemy when in brush now all you have to do is stay in the brush and wait for minions to get low and just jump to them and get back in the brush and repeat. This also gives you a great opportunity to jump at you enemies and surprise them with you amazing burst damage.

Pros:
-Rengar's leap can prove very helpful when chasing down an enemy
-Rengar's abilities allow you to quickly burst down your enemies
-Rengar can prove to be effective in any lane
-My build helps you deal damage early, mid, late game and you can take some punishment too

Cons:
-Sometimes Rengar's leap can put you in an awkward position.
-Rengar's Ferocity mechanic can sometimes be overwhelming when first playing him