AP Rengar is a strong high-risk, high-reward pick. He is strong early game and most likely will dominate if you are good. If you suck at league, gl xD (jk). This guide will show you that AP RENGAR IS NOT A TROLL PICK. When played correctly, you can domiate early, causing you to win the game easier.

To farm with AP Rengar, is to Auto Attack (AA) and then W. Once you have reached higher levels, try to AA, Q, then W. If the skills are on cooldown (cd), just AA. If you really need help on farming, practice AA'ing when the minions are low HP.

Rengar Pros
[*] High sustain
[*] Has potential early game
[*] Can farm pretty well
[*] Not ultimate dependent
[*] Not too item dependent
[*] Potential to burst w/ 5/5 ferocity
Rengar Cons
[*] Falls off late game
[*] E is almost useless
[*] Can be countered easily

Unseen Predator
While in brush or stealth Rengar will leap at the target when using his basic attack. Rengar builds 1 point of Ferocity with each ability he uses on enemies. When reaching 5 points of Ferocity, Rengar's next ability becomes empowered, granting it a bonus effect.


Savagery
Cost: Builds 1 Ferocity
Range: Self
Rengar's next basic attack deals bonus damage.

Ferocity effect: Rengar deals enhanced damage and grants him Attack Speed and Attack Damage.
The next basic attack within 3 seconds deals 100/105/110/115/120% (0) of Rengar's Attack Damage plus 30/60/90/120/150 physical damage.
Ferocity effect: The next basic attack within 3 seconds deals 150% 1 of Rengar's Attack Damage plus 0 physical damage and grants [0]% Attack Speed and 10% Attack Damage for 5 seconds (Damage and Attack Speed scale with Rengar's level).


Battle Roar
Cost: Builds 1 Ferocity
Range: 500
Rengar lets out a battle roar, damaging enemies and gaining bonus Armor and Magic Resist for a short duration.

Ferocity effect: Rengar heals for a large amount.
Deals 50/80/110/140/170 (+80% Ability Power) magic damage to enemies in the area. Rengar's Armor and Magic Resist are increased by 10/15/20/25/30 for 4 seconds. The bonus Armor and Magic Resist is increased by 50% for each enemy Champion or large Monster hit.
Ferocity effect: Deals 0 (+80% Ability Power) magic damage to enemies in the area, grants the defenses from the normal ability, and restores between 0 and 0 Health based on missing Health (healing and damage values scale with Rengar's level).

Bola Strike
Cost: Builds 1 Ferocity
Range: 1000
Rengar throws a bola, slowing the first target hit for a short duration.

Ferocity effect: Roots the target.
Throws a bola dealing 50/100/150/200/250 (+70% bonus Attack Damage) physical damage and slowing an enemy by 60/65/70/75/80% for 2.5 seconds. This slow diminishes over time.
Ferocity effect: Deals 0 (+70% bonus Attack Damage) physical damage and roots the target for 1.75 seconds on top of the normal slow (damage scales with Rengar's level).


Thrill of the Hunt
Cost: Builds 5 Ferocity
Range: 2000/3000/4000
Rengar activates his predatory instincts, stealthing himself and revealing all enemy Champions in a large radius around him. While stealthed, he gains Movement Speed when he moves towards enemies and his next attack will cause him to leap. He gains Movement Speed and rapidly generates Ferocity after he breaks stealth.
Rengar stealths himself for 7 seconds after a 1 second (delayed to 3 seconds if taking damage) delay and reveals enemy Champions within 2000/3000/4000 range. While stealthed, Rengar gains 15% Movement Speed when moving toward enemy champions and his next attack will cause him to leap.After breaking stealth, Rengar gains 25/35/45% Movement Speed and generates 5 Ferocity over 5 seconds.

From http://gameinfo.na.leagueoflegends.com/en/game-info/champions/rengar/

The summoner spell Teleport may be used in different ways.
One way is to ult (R), then Teleport right after, so you are unseen and teleporting. This is a tactic that can surprise your opponent.
Another way is to teleport and ult right after, so they feel nervous.
The final way is to teleport and just simply burst with your Q, W, and E, with AA's.
Using ignite
Use ignite wisely, only ignite if you KNOW you will get the target. If you think they may escape, you might as well save it for later. However, if they are diving, you may want to ignite the target whom is taking the turret shots.

If you are being tower dived and you have over half health, you should try to obtain 5/5 ferocity, to heal with W. If you cannot, you may as well try to fight the one who is taking tower shots. If the one who is tanking the turret attacks is over 2500 health and is a tank in armour, do not attempt to 1v1 under the turret. You have a significant chance of losing. However, if it is a squishy mage or fighter, kill 'em. Unless it is Tryndamere (fighter), you are fine.

AP Rengar is an addicting champion to play and I really suggest you play him! Good luck on the Rift, Summoners, and I may see you there ;)
See you until the next guide!