Hello!

First of all, this is my first guide to any champ, and I'm sure it has its flaws (don't flame, constructive criticism is wellcome).

The idea of making a guide came to me when I started playing jungle Rengar recently and found it damn frustrating with the current jungle. Mostly because of low sustainability at the first levels I didn't get to gank much and felt really useless. I tried few builds here on mobafire but they didn't work for me. Either they had too low defence or attack to clear jungle and still have enough hp to gank in the earlier levels.

This build has, in my opinion, a good balance between defence and offence so you can clear the jungle safely and have enough hp to do ganks even at lvls 2,3,4,5.

I go for armor seals, good for extra dmg reduction from monsters and enemy champs.

I take 4 armor pen marks which is about 5 arp, combined with 5 form masteries I can shred through even the bulkiest jungle monster's armor. 5 AD marks give me more dmg and a faster clearing time and abit more dmg for ganks/counter jungling etc.

M. res. per level glyphs provide some defence agaisnt ap champs,

Movement speed quints are my favorite quints for jungling, helping catch up fleeing enemies and reduces time spent moving between jungle camps. These can also be replaces with AD/attack speed to make you clear the jungle even faster.

For masteries I use 21/9/0, taking physicalk dmg buffs, cooldown reduction and minion dmg boost from attack, and health and jungle masteries from defence.

These masteria combined with the runes give a good potential for high damage aswell as reduced damage from monsters to make jungling fast and safe.

The items up to mid game are a must, they gove a good deal of dmg, utility and defence.

After this having these I buy either atmog's or Malmortius, depending on the enemy team.

Finally I buy some armor pen, so it's either black cleaver or last whisper. Personally I like black cleaver more duea to it's cd reduction, health and higher dmg.

Default jungling route would be Wraiths -> Lizard -> Golems -> Wraiths -> Wolves -> Blue

but I usally go either red or blue depending on where I think the enemy jungler goes. If he goes to blue, I go to my blue and then to his red and either try to kill him there or if he goes staright to gank from blue I take the red. If it's succesfull I'll also try to clear as much of his jungle as possible. For example if I play bot and the enemy goes straight from blue to gank bot I have alot of time to take big golem and the wraith, leaving him behind in exp and money.

If enemy goes to red I'll try to get my team to invade if possible. Otherwise I go for my wraiths/red and then their blue/wolves -> gank if possible

You should always buy some wards especialyl the first time you go to shop, even if you get the lantern. Ward some of the critical points in enemy jungle (red, wraiths, blue, golems) and harras/counterjungle/kill him in addition to lane ganks and farming.