Alright so first off, when you play Rengar it doesn't matter if you go top or bottom just never go mid. You first get someone to leash red buff for you which red helps you and gives you extra EXP and generates some ferocity, and then you go to your lane. While your in your lane stay at about 4/5 ferocity and let your teammate initiate the fight for you because Rengar is a bit squishy but has massive damage burst. Once your teammate initiates you leap out of a bush use savage on the squishiest enemy target then use it again WITH the FEROCITY boost, and also unleash your other skills out on the target which leads to an easy kill.

Pros : Insane damage bursts, Fast Speed, Good escapes/Ganks.

Cons : Quite Squishy if not played well, a bit slow at start, if not fed you won't enjoy him.

Speed as Rengar is important as well is damage. The only reason I don't include much attack speed in my build is because of the savage attack speed boost which is deadly. At end game build you end up with somewhere around 400 AD, 1.6 attack speed, 40% Critical Chance, and 500 Movement Speed.

When you farm, and you are sure there are no enemy champions around unleash all your skills on the minions and when you gain 5/5 ferocity use your howl to do AOE damage to all the minions and eliminate them quickly. If there are enemy champions around stay aware that they might try to attack you if you push too far, but if they back up out of your sight unleash everything on minions, but try to stay at 3/5 or 4/5 ferocity so you can have quick burst damage if someone tries to kill you.

My choice in Summoner Spells is simple as is my rune choice, when playing Rengar having ghost is good to go with his ultimate. For Example : One day I was chasing down wee little teemo and he had low HP but was nearing a turret, so I blew my ghost and my ultimate and let it gain 5/5 ferocity then leaped him savaged him and ignited and left him to die. But at the start use ghost as an escape tactic.

My choice in runes is simple, basically in the start if you have a lot of extra damage as Rengar, your savagery will deal massive damage and will scare off the enemy and it also gives you a greater chance to get a kill at the start with all of that AD.

My Masteries are damage based because at the start, the more AD you have the higher a chance you have to kill an enemy target at the start of the round letting you be more fed which eventually leads to even more kills as Rengar.

This pretty much raps up my guide to a good Rengar, but I still have a few tips for you. As Rengar when you are trying to run out of trouble use ghost and your ultimate to gain a great speed boost, use your ultimate ferocity gain to your advantage; let it go to 5/5 then leap at a squishy target if he is alone and unleash everything you got on him. And last on the list; If you're playing against a tank who builds to counter you, instead of buying a phantom dancer get a Last Whisper. This ends my guide to Rengar, thank you for taking the time to read it and all. :)