Welcome to my first mobafire guide.
In this guide I will show you how to build Rengar as a high-damage champion that also has good survivability and mobility.

Let's start with his skills.

P:

Unseen Predator - While in bush or stealth Rengar will leap at the target when using his basic attack. Rengar builds 1 point of Ferocity for each ability he uses on enemies. When reaching 5 points of Ferocity, Rengar's next ability becomes empowered, granting it a bonus effect.(No cost - No cooldown)

Q:

Savagery
Rengar's next basic attack deals bonus damage and grants him increased attack speed for 3 seconds.

Physical Damage: 30 / 60 / 90 / 120 / 150 (+1.0 per attack damage)
Attack Speed: 30 / 35 / 40 / 45 / 50 %

(No cost - 6 second cooldown)

EMPOWERED
Savagery deals bonus damage equal to 150% of Rengar's attack damage, and the Attack Speed bonus is doubled.

Empowered Physical Damage: 30 / 60 / 90 / 120 / 150 (+2.5 per attack damage)
Empowered Attack Speed Bonus: 60 / 70 / 80 / 90 / 100 %

(Cost: 5 Ferocity - No cooldown)

W:

Battle Roar
Rengar lets out a battle roar, damaging enemies and gaining bonus armor and magic resist for a short duration.

Magic Damage: 75 / 120 / 165 / 210 / 255 (+0.8 per ability power)
Bonus Armor & Magic Resistance: 20 / 30 / 40 / 50 / 60

(No cost - 15 / 14 / 13 / 12 / 11 seconds cooldown - 500 AoE Radius)

EMPOWERED
Battle Roar also heals Rengar for 15% of his maximum health. (Cost: 5 Ferocity - No cooldown - 500 AoE Radius)

E:

Bola Strike
Rengar throws a bola at his target, slowing them for 2.5 seconds. The slow decays over the duration.

Physical Damage: 60 / 105 / 150 / 195 / 240 (+0.7 per bonus attack damage)
Slow: 50 / 55 / 60 / 65 / 70 %

(No cost - 12 / 11 / 10 / 9 / 8 seconds cooldown - 575 Range)

EMPOWERED
Bola Strike initially roots his target for 1 second. The slow is applied in full after the 1 second, and decays over the remaining 1.5 seconds. Crowd control reduction will reduce each duration separately.(Cost: 5 Ferocity - No cooldown - 575 Range)

R:

Thrill of the Hunt
Rengar activates his predatory instincts, stealthing and revealing all enemy Champions in a large radius around him. He gains movement speed and generates 1 Ferocity per 0.75s while stealthed. Lasts 7 seconds or until he uses an ability.

Vision Radius: 2000 / 3000 / 4000
Movement Speed Bonus: 20 / 25 / 30 %

(No cost - 120 / 85 / 50 seconds cooldown)

Runes and masteries are basic.
Flat attack damage marks, seals and glyphs along with AD/Level Quintessences for maximum damage.
For masteries I picked 21-9-0 taking attack damage masteries on the Offense tree and getting Veteran Scars on the Defense tree along with some magic resist and armor.

This is the order in which you should buy the items
NOTE: This order is meant for a good case scenario, buy them in this order if you are doing well in the game, I will tell you in what order to buy if you aren't doing good enough.

1.As a starting item I pick up a Doran's Blade for some starting attack damage and decent lifesteal.
Why Doran's Blade?

This will be your only source of lifesteal untill a certain point of the game, it also gives you good stats for the early game, hold on to it untill you can replace it with a better item.

2.The next item is Boots of Speed upgrading it to Boots of Mobility immediately if you are doing good. If you are having trouble surviving upgrade to Boots of Mobility after you purchased a Phage.
Why Boots of Mobility?

As Rengar, you are not as fast as other champions, you require these boots in order to catch up with fleeing enemies or to escape any dangerous situations more easily than you would with the standard Movement Speed 2 boots.

3.For the third item a Bonetooth Necklace is a great choice, it gives you great bonuses for your skills and stats and an early pick-up will give you more time to stack it up to it's maximum potential throughout the game. If you aren't doing well in the game then skip this item and get the 4th one. Don't get it until you are sure you will be able to get stacks on it.

4.For the forth item I take a Frozen Mallet, not only it gives you great survivability, but it also gives you some attack damage and more chase potential with it's passive slow/hit. Even if you aren't doing well you definitely don't want to skip this item.

5.No reason to say why to get a Bloodthirster, it gives attack damage, it gives lifesteal, it gives bonus AD and Lifesteal per minions/champions killed with a cap of 40 stacks (at 40 stacks it gives 40 AD and 8%). It's a good pick.

6.For the sixth item I pick up a Black Cleaver for it's attack damage, attack speed and its great passive armor reduction.
Why Black Cleaver?

For picking up Boots of Mobility you are lacking the attack speed bonus of Berserker's Greaves, in order to make up for that you need an item that gives you good attack speed, but also attack damage, that's why we don't just pick up a Zeal or Phantom Dancer, besides it also gives a great passive, and the passive will truly shine with the attack speed bonus of your Q

7.At this point you might be wanting to replace that Doran's Blade we picked up at the start of the game with whatever you like, for this build I usually pick up some more survivability, I take a Guardian's Angel for it's balanced defenses for both AD and AP champs, it's passive is also great when you get focused. Feel free to replace it with a Force of Nature if you are having trouble against AP enemy champs or a Thornmail for AD enemy champs.

Thank you for reading my guide, I hope you enjoyed it and found it helpful.

Guide created by FoohyMasterr from EU West.