“Rengar can be a tough TOP laner to go up against if he does go top, he's primarily a JNG. It's quite simple really. Let him win the lane. You can not do anything to him and he is efficiently capable of zoning you out of minion CS range. Just let him push and farm under your tower. Sidestep or use your minions to body block his bolas, or be snared/slowed and chased down. It may be demoralizing but this is what you absolutely need to do to survive this lane, please do not try to be some hero, unless he is mentally incapable of playing the champion correctly by camping bushes, then you lose this HARD. His (R) will reveal you so don't play passive game once he is 6.
“TL;DR - EASY LANE. DON’T TAKE STUPID FIGHTS AT LEVEL 1/2 WHEN HE HAS FEROCITY STACKS. DON’T LET HIM WALK AWAY FROM TRADES. FREE AFTER LEVEL 3. STEELCAPS IF LOSING.
A Rengar matchup depends on how good the Rengar is. Joe Schmoe who builds lethality every game is going to be free food compared to a Dekar but generally speaking, Darius is one of Rengar top’s biggest counters. All you have to do is to make sure he does not cheese you level 1. Just stand outside of his jump range from bushes. If you don’t know the range, just hop into practice tool on Rengar. Level 1, it is best to give up unless you catch him outside a brush. And even then, Rengar wins hard, especially if he has ignite. Respect his 4 stacks.
Once you hit level 3, the lane should be over. If the Rengar keeps playing aggressively and does not adjust his playstyle, he is free food. The second he goes in for a minion, Q-AA-W, pop ghost and then just mess him up. Try to dodge his E root and be mindful of where the Rengar can jump in order to stop him from outplaying you. If he does a W+Empowered W, just E him back. There is no hope for a Rengar to win this lane. What most GOOD Rengars will do is go for W max and essentially beat you out by attrition because a W+W leads to them taking zero damage and you taking more damage than him. Rengar’s tactic would be to utilize his W to cancel your slows and heal back up the damage you deal to him as a way of poking you down. Just don’t let him walk away for free. Land your Es. Phase Rush works but I prefer Conqueror to help me punch through his healing. One last thing is to keep in mind that he is deceptively tanky. If you ult him and it DOES NOT kill him, he will just heal back ALL of the damage if he has his w up.”
“Can be flung mid-leap for some wacky interactions. Generally speaking an easy kill if he ganks you so long as he doesn't land either his E or empowered E. Can be baited into jumping from the closest top lane bush into you flinging him under tower range. Laning against Rengar you should avoid those top brushes and hard shove the lane if he's not too oppressive. A Rengar under tower is much nicer than one with access to bushes.”
“Similiar to Irelia but a little weaker for an All in. Stay away from the bushes and you should be fine. Rush Ninja Tabi.”
“Try to push fast lane don't let him control bushes cuz he will outdamage you so hard. His W is denying your stun and healing him back from all your dmg you dealt to him. Fast rush tabi and tiamat to outpush waves. Your E block his Q.”
“Opt to build tank against Rengar, Rengar has a lot of burst damage potential if he is near the brush. Use Mega Adhesive to prevent Unseen Predator(Passive). (Recommended Items: Plated Steelcaps, Rylai's Scepter) (Sustained 1v1 Battles: Even) (Outscaling Edge: Singed) (Mega Adhesive prevents Unseen Predator) (Fling can override Unseen Predator)”
“Do not fight him lvl 1, sit back and let him jump around. You want to parry his empowered Q and dont be afraid to chase him down afterwards to punish him. When he ults, parry as soon as he lands on you. You should win if you ult right after to finish the job.”
“Don't fight this guy Level 1, he just wants to cheese you, so kindly deny him. But I mean, if he doesn't have ignite you can win Level 1 if you sit in a bush waiting for him and learn W. I remember forcing a high elo Rengar one-trick Level 1 to flash by doing this and they all chatted right after "WTF why didn't I beat you lv 1?" Past Level 6 you auto-win because his ult is useless when compared to yours in a 1v1. He still might be able to get away from CC with his built in cleanse or ult invis though. Rengar will become a threat if he roams and gets kills on your team, or you let him get free plates. Pushing into his tower makes it so he can't bush cheese you, that's the best strategy to fight him past level 6, just stack a wave VS him that will slow push towards him then never let him walk up. Be careful of JG ganks, but in all honesty, you can probably win a 2v1. Just rush Bramble Vest and Plated Steelcaps, and first item Trinity Force since he's squishy. Go Death's Dance 2nd item if the enemy has another AD, or 3rd item if he is the only AD. ”
“Rengar relies on cheese to lane. Darius is a hard counter to him because Rengar cannot take short trades to burst us down, we just pull him back in and trade better.
Easy lane. Beware of level 1 though.”
“Opt to build tank against Rengar, Rengar has a lot of burst damage potential if he is near the brush. Use Primal Howl or Infinite Duress to prevent Unseen Predator(Passive). (Recommended Items: Plated Steelcaps) (Sustained 1v1 Battles: Even) (Outscaling Edge: Warwick) (Jaws of the Beast can follow Unseen Predator)”