Use Rengar's strong early dueling and high invade resistance to aggressively contest river brush and enemy camps when your lanes hold priority.
Focus on brush control and stealth picks with (R) to deny Nunu's objective tempo and force numbers advantages before dragon or Herald fights.
Jungle Plan
Invade Nunu's jungle early when your lanes can cover your exit to deny his fast clear and objective control.
Fight for river brush control before dragon or Rift Herald spawns to set up picks and secure vision.
Use (R) stealth to create picks on isolated targets, then convert those into immediate objective pressure or counter-jungling.
Danger windows
Avoid fighting in open river areas early where Nunu can engage with (W) and root with (E), especially if lanes lack priority.
Beware forced Smite fights at dragon or Herald when Nunu's (Q) sustain and objective secure combo is strongest.
Be cautious during low-health clears or after failed invades as Nunu's gank threat and objective control spike can punish overextensions.
Early game
Start with a three-camp clear through brush-heavy routes to maximize level 3 strength and early invade potential.
Only contest first Scuttle if nearby lanes have priority to avoid Nunu's potent early ganks and objective setups.
Avoid isolated river fights where Nunu can engage with (W) and root with (E); instead, seek brush ambushes and counter-invades.
Power spikes
Hit level 6 to unlock (R) for high gank threat and pick potential; use it to force carries to respect fog and create skirmish advantages.
Respect Nunu's first dragon or Herald spawn timing when his (Q) plus Smite secures objectives quickly; contest or punish him if he shows opposite side.
Beware Nunu's level 6 (R) zone control during ganks and objective fights; avoid getting caught in his CC chain to prevent burst damage.
Win conditions
Convert brush control and successful (R) picks into immediate dragon or Rift Herald attempts to snowball map pressure.
Use superior dueling and invade resistance to deny Nunu free camps and force him into reactive play.
Leverage post-6 gank threat to pressure sidelanes, create picks, and secure objectives before Nunu can group and use his utility engage effectively.
Tip: For Rengar vs Nunu & Willump, read overview, trading pattern, and danger windows first for a fast Jungle lane check.