AP Rengar very poxerfull in 1 v 1 situations. He can easly instakill with this combo:

Be at 3 or 4 ferocity then use passive Unseen Predator with Thrill of the Hunt or via bush then Deathfire Grasp double Battle Roar ( Lich Bane/ Savagery )and Ignite if needed. This combo does approximatly 3400dmg with ingite ( double Battle Roar with 840AP does 2000dmg but dont forget magic ressistance and lich bane thats deals 500 dmg on landing )

Savagery COOLDOWN: 6 / 5.5 / 5 / 4.5 / 4
ACTIVE: Rengar's next basic attack in the next 3 seconds deals modified physical damage.
MODIFIED PHYSICAL DAMAGE: 30 / 60 / 90 / 120 / 150 (+100 / 105 / 110 / 115 / 120% AD)

Empowered Savagery COST: 5 FEROCITY
ACTIVE: Savagery deals modified damage equal to 30-240 (+ 150% AD). Additionally, Savagery grants Rengar bonus 47 + (3 × Rengar's level) % attack speed and increases his attack damage by 10% for 5 seconds.

Ability Details
Savagery and Empowered Savagery are self-buff on-hit effect abilities.
The triggering attack will apply other on-hit effects and can critically strike as normal.
As with most on-hit physical damage, the bonus damage from Savagery and Empowered Savagery will apply life steal.


Battle Roar RANGE: 500 COOLDOWN: 12
ACTIVE: Rengar lets out a Battle Roar, dealing magic damage to nearby enemies and increasing his armor and magic resist for 4 seconds.
MAGIC DAMAGE: 50 / 80 / 110 / 140 / 170 (+ 80% AP)
ARMOR & MAGIC RESISTANCE: 10 / 15 / 20 / 25 / 30
Rengar gains additional armor and magic resist for each enemy champion or large monster hit.
BONUS PER CHAMPION/MONSTER HIT: 5 / 7.5 / 10 / 12.5 / 15

Empowered Battle Roar COST: 5 FEROCITY
ACTIVE: Battle Roar deals modified damage equal to 40-240 (+ 80% AP). Additionally, Battle Roar heals Rengar for 8 + (4 × Rengar's level) health, increased by 6.25% for every 1% of Rengar's missing health for up to 50 + (25 × Rengar's level) health.
Battle Roar and Empowered Battle Roar bonus defenses do not stack with each other.

Bola Strike RANGE: 1000 COOLDOWN: 10
ACTIVE: Rengar throws a bola in the target direction, dealing physical damage and slowing the first enemy hit for 2.5 seconds. The slow decays over the duration.
PHYSICAL DAMAGE: 50 / 100 / 150 / 200 / 250 (+ 70% bonus AD)
SLOW: 60 / 65 / 70 / 75 / 80%

Empowered Bola Strike COST: 5 FEROCITY
ACTIVE: Bola Strike deals modified damage equal to 50-340 (+ 70% bonus AD). Additionally, it roots the target for 1.75 seconds.

Thrill of the Hunt COOLDOWN: 150 / 110 / 70
ACTIVE: Rengar activates his predatory instincts, gaining stealth after 1 second (delayed up to 3 seconds if taking damage) and vision of all nearby enemy champions for 7 / 12 seconds or until Rengar damages an enemy with one of his abilities or basic attacks.
VISION RADIUS: 2000 / 3000 / 4000
While stealthed, Rengar gains 15% / 30% bonus movement speed while moving toward an enemy champion. Enemies are made aware that Rengar is nearby if he is less than 1250 units away.
Upon exiting stealth, Rengar gains unconditional bonus movement speed and generates 5 Ferocity over the next 5 seconds.
MOVEMENT SPEED: 25 / 35 / 45%

As AP Rengar most of your dmg is provided by Battle Roar its the only ablility that scalls on AP so max it first. In laning phase try to farm as much as possible without getting poked to much, and keep in mind that your Savagery still does a decent amount of dmg in early game so you can farm and poke better.What you should do to poke the enemy is get to 3 to 4 Ferocity go in a bush and use your passive Unseen Predator to jump on enemy or on minion to get close to your enemy to poke or kill him with the double Battle Roar or Savagery and then double Battle Roar.If you havn't killed him yet just wait until he's low and off guard and then jump on him double Battle Roar and ignite( when you are lvl 5 or 6 if he has a bit less then half of his hp it should kill him).

When you have Lich Bane and Deathfire Grasp you can instakill the squishies, so if you are winning your lane and you have destroyed there first tower it's time to roam.Roam to the lanes to help your partners get fed or come back in the game.Before a team fight you should try and catch there carries (midlaner or adc) if they are isolated from there team, just use Thrill of the Hunt Unseen Predator Deathfire Grasp double Battle Roar Lich Bane Savagery and Ignite if needed. In lane team fights you can do two things:

You can ult engage with 3 or 4 ferocity on the carries or if team fight is located in jungle use

Unseen Predator via a bush and then zhonia if the team didn't insta followed if not continue doing as much dmg as possible
Or just let your team engage wait until everybody low jump in the middle and do as much dmg as possible with double Battle Roar that does AoE dmg.

In early game try just to last hit with Unseen Predator or Savagery and try not to push to hard or you wont be able to poke him thanks to brushes and you would be pretty vulnerable to early ganks because you have no ult yet. Later in the game it get pretty simple to farm as AP Rengar when you have a some dmg on Battle Roar just go in the middle of minions and double Battle Roar for instant farm keeping in mind that Battle Roar range is pretty big and you could poke your enemy if he's too close or he's a melee to the minions you want to kill.

Pros: With this build you do massive single target dmg and a little bit less AoE but still massive dmg.
Very good laning phase and easy farming with double Battle Roar and easy early feed

Cons: You cannot stay in teamfights forever because after you used your combo you get easly killed also while 1 v 1
You are not tanky and have no life steal

I prefer to play with Ignite because it helps you have early kills, then Heal because you have an integrated heal in your max ferocity Battle Roar that heals you for (12 + (4 x level) + (6.25% per 1% missing health)

Max your Battle Roar first of course, only ability that scalls on AP like i said earlier, then Savagery that still does a decent amount of dmg in early and that does much dmg combied with Lich Bane.