Nocturne is one of the most amazing gankers in the game, with a lifesteal passive, which qualifies him as a jungler. Most people i have seen don't prefer to jungle nocturne because the golem is so ridiculously hard. But nocturne can be jungled, and he can be jungled well.
The items i am listing have worked for me in EVERY game i have played as nocturne. I take boots of mobility over zerker greaves because the added speed allows me, the ultimate chaser, to catch anyone and be anywhere on the map at any time, that, and he moves so F***ing cool when he has fast movement speed. The Bloodthirster combined with wriggles allows you to have just enough lifesteal to get out of a stun or fear and still manage to keep yourself alive and kill the *******. Trinity force is probably one of the best items in the game, with the movement speed (which i love), the 150% damage proc, and the slow. After trinity force you should be an unstoppable killing machine. As for banshees veil, i love it, but your W skill is an amazing spell shield with a bonus for catching a spell, also it has a shorter CD then banshees.
Items in order:
5 Hp pots
Cloth Armor---->Madreds Razors
Boots of Mobility
Madreds Razors---->Wriggles lantern
From there it should be game over, but if your having one of those crazy long games with both sides going neck and neck, then items you should consider:
Infinity edge- with the crit from trinity force and the extra 20% here you will be looking at insane crits around 1200 or 1300 just after this.
Guardians angel- Probably one of my favorite items in the game, why last a little bit longer when you can just have 2 lives? After this you can get up, find the people who, if they focused you, will be attacking your teammates. Attack them and heal up with your lifesteal as they wonder if they really just killed you.
Ghostblade- The first thought is "Why didnt he add this into his core items? This guy must be terrible." Heres why, personally, i am not one of the low dmg, high attack speed guys. I like to hit someone and hit them hard. Second, nocturne has naturally high attack speed with his W giving 40% AS and double that if you absorb a spell. Third, im always forget to activate it...but for those who love this item, go ahead, the Armor penetration, movement speed, and attack speed add for a nice boost when ganking and team fighting.
Banshees veil- Contrary to what i said earlier, this item isnt BAD for nocturne, but Guardians angel has always been a preference to me.
Big golem (Blue buff)
(Depending one how well you jungled go small golems or back to base.)
Afterwords i like to continually farm the jungle until i have madreds razors and boots before i gank. But if someone on the other team is over extending in any of the lanes, dont be afraid to go gank them with you awesome lizard buff slow, just be warned that nocturne is SO slow without boots and its hard to catch them.
First, after you enter a game head down to blue buff and make sure you have someone gaurd you. When golem spawns have your teammate attack him first, then run around for a few secs, and then have him run away so that he does not get your needed exp. (This is called leashing for those who did not know.) Make sure to pop your health pot as soon as you get hit by the golem when you teammate leaves. You should finish the golem with around 2 or three bars, maybe 1 depending on the length of the leash. Finish off the two mini minions and head to the wolves with a pot on you if the other wore off.
When at the wolves line up your newly aquired Q skill and hit them, make sure to stand in the spot you shot it or inside of it because you grab a nice Attack damage buff from the ability. After those are done head down to the wraiths, remember to keep a pot on you at all times. When at the wraiths once again aim your Q to hit all of them then attack the big wraith, make sure you get him down first because he hurts. After that you should be around 3/4ths hp and going up because of pots, if any lower no worries, just wait a bit by the lizard for the pots to bring you up.
Now that you are at lizard, and around full hp, the second hardest part of your explorer jungling fun time adventure is here. the lizard hits very hard, just like the golem, open up with your Q and attack the lizard. then as soon as you attack him use your E on him to do some damage and cause him to be feared, these precious moments of fear may save your life. Continually spam Q and E and don't forget about your health pots, remember to have them up. If you are having a little trouble here it may be because the golem got you a little too low, have your partner stick around for a tiny bit more before he leaves.
After lizard depending on your HP you can gank or mini golems, as i said before you are SLOW AS ****.
1/1 Improved smite
2/2 Offensive mastery
3/3 Brute force
1/1 Improved ghost
4/4 Awareness (exp thingy)
1/2 Utility master
For runes i have Crit reds, Attack speed yellows, Crit damage blues, and crit damage quints, mainly because i love crits!
Edit: Yes armor penetration is better, but this is just the rune page i made when i hit lvl 20 and i will change it, but for now just saying it works.
Hope you have fun, this is mainly just my personal preference for a build on a charecter who can fill many roles.
Any comments/feedback appreciated!
Edit: Yes you NEED to have someone leash the golem to be able to jungle this champion, but thats not to much of a problem in any game, normal or ranked.