This is how i play Nocturne.

I Have played Nocturne pretty much in Ranked, and a lot in Normal Game, and i think he is one of the better champs in the game. I'm not saying I'm the super awesome #1 Nocturne or anything... This is just the way i play him and it works good for me. Hope you all will try it and find it good, just like me. And don't forgot to give a vote and a comment!

This is my first guide, so if anyone notice anything wrong.. Tell me!
And for god sakes, sorry for my bad English!

Marks:
2 Armor Penetration
7 Attack Speed
Seals:
9 Armor
Glyphs
9 Magic Resist/LvL
Quints:
3 Armor Penetration

Attack Speed: 10%
Armor: 13
Magic Resist at Level 18: 24
Armor Penetration: 15

With all the items, this works out really good.
Armor for the jungle and early ganks, works nice.
Attackspeed for clearing the jungle and help his passive to procc faster. Noc + Attackspeed = amazing.
Magic Resist. I use MR/Lv, because AP is better late game, and you will be in the jungle early so you dont need the magicpen early. The runes are better then the flat ones after like Lv 7-8.
Armorpen. You wanna kill everyone. With armorpen in runes and the items ur gonna do whatever u want.

You can switch around with the Armorpen and Attackspeed until you are happy, but i find this most fitting for Nocturne.

This is my 9-21-0 Masteries for Jungle Nocturne. I use these most of the time. I like the tankyness on Nocturne, easy jungle and great sustain. Movementspeed for better ganks. You want to survive a dive when you play the best diver in the game.
This is my 21-9-0 Masteries for Jungle Nocturne. I use those for faster jungle and good dmg. ArmorPen is amazing on Nocturne, and i pick Life Steal instead of 1.5% more dmg for the synergy with his passive.

I use Flash and Smite.

Why Flash?
You got movementspeed from Duskbringer, so Ghost is not needed. It's better to use flash to escape or jump into teamfights.

Why Smite?
You are jungling, right? AND IF YOU ARE JUNGLING YOU WILL TAKE SMITE, OK? COMPRENDE? BLABLIBU? Not only for faster jungle, it's also securing Baron, Dragon and buffs. And also for stealing!

You can also use Exhaust, Ghost or something else, but this works best imo.

Summoner Spells you DONT want to use are:
Heal - I know it got buffed, but it's not suitable for junglers.
Clarity - Your "manaissues" only exists in the early, but you are going to have bluebuff.
Clairvoyance- Give that to the support.

Start with Boots of Speed and three healthpots.
At first back you want to get Scepter, some wards and maybe some potions. If you have gold, you can get Recurve Bow.
If you want you can buy an early Heart of Gold before you start with Wit's End. It's good health and gold/5.

Q-W-Q-E-Q-R

Max Q first. Nothing else to do. After that i max my Fear-spell, because the shield doesn't really make another thing else than double the attackspeed when procced... Not as good as the fear imo, but my friend takes shield before and it works but not the better choice imo.

umbrablades
Umbra Blades
Every 10 seconds, Nocturne's next attack strikes surrounding enemies for 120% of his physical damage and heals himself for 15/20/25 per target hit. Nocturne's autoattacks reduce this cooldown by 1 second.

Great passive for a jungler! And with attackspeed, it's even better! Good for farming and AoE-damage in teamfights. I love it!


Duskbringer
Nocturne sends a shadow blade in a line that deals physical damage to all enemies it passes through, leaves a Dusk Trail on its path, and causes champions who are hit to also leave a Dusk Trail when they move for 5 seconds. While on the trail, Nocturne ignores unit collision and has increased movement speed and attack damage.

This skill is amazing. Just 2gud. You cant find a reason not to use this 24:7. If you do please send me a message (except for wasting mana ofc brobro). I just cant see it. Move faster while chasing/escaping, do more damage on everyone and everything (+AD. freakin amazing). Take down turrets/inhibits easier, gank easier.. Its just an great skill. And! It's a skillshot. You can cast in wherever and whenever you want. It has been nerfed hard since Nocturne was released but cmon.. Still pwning!


Shroud of Darkness
Passive: Nocturne empowers his blades, permanently gaining attack speed.
Activate:Nocturne creates a magical shield for 2 seconds which can block the next enemy spell that hits him. If an ability is blocked by the shield, his passive attack speed is doubled for 5 seconds.

This. Shield. Is. Insane. Why? You can stop 1 skill whenever u want. And it even stops ults! The only annoying thing is that it wont stop things like Zileans bombs if they are on u. You have to use the shield before the bomb got attached to you. Anything else is pretty easy to dodge. And really, it isn't hard to calculate when Zilean is using bombs.


Unspeakable Horror
Nocturne plants a nightmare into his target's mind, dealing magic damage over 2 seconds and placing a leash on the target for the duration. If Nocturne stays within leash range of the target for the full duration, the target becomes feared.

I think this is unnderrated... It can be used anytime. It makes your jungle after Lv4 easier. It saves you *** if you are being chased. It makes ur ganks like a good night sleep. I mean... I have killed with this. Chasing a low-health champ and he/she died of it. Pretty funny.. Dont underestimate the damage from it.


Paranoia
Nocturne reduces the sight radius of all enemy champions and removes their ally vision for 4 seconds; this includes champions, minions, wards, towers, and clairvoyance.
While Paranoia is active, Nocturne can launch himself at a visible enemy champion, dealing physical damage.

I dont think i have to say anything. It have been nerfed many times but i still thinks it's a good ultimate. Makes ur opponents mapawareness become zero. And i dont know if many people know this, but if a opponent is dying from a turret, u can pop this ult to get the kill. I accidently did this on a botgame. 2 gud.

Q + E + W = Dead. Use ultimate if they run away.

And yeah, you can open up ganks with the ultimate but if they flash away u gotta use flash to, and thats not a good thing uknow.

Early:
Wolfs > Blue > Wraiths > Wolfs > Red > Golems/Wraiths > Whatever

Gank when possible, but you really want to be in Lv6 asap.

Mid:
Kill minions in jungle when u can. But don't just take out one camp. Take out everyone of them so they spawn together. It's not like ur gonna fail in the game if you don't do this but it's better for everyone. Prioritize the ganking and fights. Aware dragonkills and u want'em. Take the dragon when u can. Bot can help u if you feel like u cant take him alone.

End:
U see dat carry? U dont wanna make dat carry killin u team?
Pop dat ultimate and kill dat carry, and then GTFO. You did you job. Without their carry and/or caster, ur team can do whatever they want. Get that tower or baron or whatever. Their main damagedealer is gone!

You want to kill that carry/caster! And who does that job better than Nocturne?

If the teamfight is on and the carry is outside and use his/her range. Abuse your ult when no-one notice. I know, pretty hard to notice Nocturne's ult.. But be fast! Kill that carry/caster and GTFO! You did your job. if you have health to stay, just stay. Help your team.

In the early/mid game, get the ganks in every lane. Don't gank just because. Dont wait in a brush until a gank pops up. Tell your mates to stop pushing, or else it is no reason to be there.

Yea.. This is my first guide. I am going to read it and change stuffs but im leaving it like this for now.

Hope this is helping anyone that want to play some bad-*** Nocturne.

Vote and comment!

Holla!

EDIT: Remade pretty much everything.. Item-order, masteries, runes and stuff like that.. Fixing more things later!

EDIT: Added the pictures and added more text to the guide for better understanding. Changed some things in the build.

EDIT: Remade Masteries, removed Heart of Gold from the itembuild, fixed Runes.