Welcome to my guide for Nocturne, the Eternal Nightmare. I will present to you a build that I have found great success with while playing this awesome champ.
Nocturne fulfills two roles on a team very well: assassin and initiator. You need to build to properly perform both these roles, as such I build him as a tanky initiator. Glass cannon builds for Nocturne are complete and total bull**** in my book. He is not an AD carry. He can get lots of kills, he can snowball insanely well, but a glass cannon build completely falls off late game since he will instantly fall under focused fire. You need to build tanky to properly perform your role as an initiator for your team.

Nocturne is an insanely fast jungler, a great farmer, an excellent assassin that has the ability to carry a team to victory. With that being said:

PROS:

• Fast jungler
• Insane ganks
• Great minion farmer, hence, insanely good pusher
• Great damage steroid, attack speed steroid and movement speed boost
• Spell shield
• Epic ultimate (DAAAARKNESS *enemies run away in terror*)
• Best counter in the game against split pushers

CONS:

• Kinda mana hungry, but correct skill usage negates this
• Tends to get focused, because he's scary >=O
• Running into a brush or breaking line of sight makes him unable to target you with his ultimate

I use armor penetration marks, armor seals, magic resist per level glyphs and armor penetration quintessences.

Greater Mark of Desolation + Greater Quintessence of Desolation - These runes shall help increased your early game damage. Attack speed marks are also good since they will help your jungle speed, but I prefer armor penetration to maximize my damage to champions since I focus on ganking a lot. Also, my item build will focus on getting pretty much flat armor penetration to increase my damage to squishies, since I want to assassinate them as fast as possible. Since he has a 55 AD steroid while on his Shadowpath, he scales very well with armor penetration.

Greater Seal of Armor - I use these for jungle safety and also to give me a little bit of tankyness early on.

Greater Glyph of Scaling Magic Resist - I got with magic resistance per level glyphs because early game, a well timed Shroud of Darkness can take away a pretty significant part of a mage's damage. Later in the game, you'll want to use your shield to block critical crowd control effects aimed at you, so you'll need to better shrug off damage from mages.

I run Ghost and Smite on Nocturne. Smite is obvious, since this is a jungle build. I prefer to use Ghost because I want to stick to squishies like glue. This spell, along with Duskbringer and Unspeakable Horror makes it very easy to do that, while also being a good defensive option as you can use it to run away when in trouble.

Other good options:

Exhaust - also helps you stick to squishies, but lacks the defensive component of Ghost.
Cleanse - ever since the Cleanse buff, it's a way better spell than before. It's a purely defensive option.
Flash - it's still a good spell. While you can use it offensively, I see it as a more defensive option for a summoner spell.
Ignite - it works, it will help you secure kills, but I feel Nocturne doesn't need extra help in doing that since it's so hard to get away from him.


Do not take these:

Clarity - overall a bad spell for Nocturne. Total waste. Avoid it like fire.
Heal - I don't care they buffed it, Heal is still bad in late game and it's countered by Ignite.
Surge - the attack speed may be tempting, but that AP it gives is just useless on Nocturne. Not worth it, in my opinion.
Clairvoyance - as said before, losing sight of the enemy makes you unable to ult them. This can counter that. But why would you waste a summoner spell slot for such a heavily situational circumstance?
Teleport - you don't need it.
Promote - lol no.
Revive - lol no again.

I run a 21/9/0 mastery setup.

I take Summoner's Wrath to improve Ghost, I take attack damage, attack speed, the +10% armor penetration, increased damage, lifesteal, increased critical chance, increased critical damage and lastly, Executioner .

In the defense tree, I take Summoner's Resolve to improve smite and I take armor and health for jungle safety.

Pretty basic masteries, really.

I take one point of Shroud of Darkness at level 1 for the bonus attack speed. The reason I do this is because I want to clear the first camp as fast as possible. Feel free to take Duskbringer, it's personal preference really. Both work.

You'll want to max Duskbringer first, since it is your main ganking tool and steroid. You need it to gank effectively and it also improves your jungle time. After that, I max Unspeakable Horror to increase the fear time. This also improves your ganking potential and gives you pretty good CC. Finally, max Shroud of Darkness and take Paranoia whenever available, obviously.

Since you'll be jungling, you can either start with a Cloth Armor and 5 Health Potions or a Vampiric Scepter. I personally prefer the armor as it makes me feel safer. Whatever you pick, you'll eventually turn them into a Wriggle's Lantern, making your jungle time insanely fast and giving you more sustain in addition to your passive, Umbra Blades.

I focus on building flat armor penetration items to maximize my damage to squishies. They rarely tend to stack tons of armor just to counter you, so it will work better than percentage armor penetration. As such, The Brutalizer is an excellent early item for Nocturne.

I prefer a defensive choice for boots, as such I always take Mercury's Treads. These are the best boots for Nocturne in my opinion, since you'll want to better shrug off any crowd control aimed at your ghostly ***.

At this point I sometimes get a Heart of Gold for the gold per 5 passive and for some health. I'll sell it later in the game. It pays for itself in around 12 minutes and a half if you sell it, so you won't be wasting any gold on it.

After that, I will build Phage and upgrade it to a Frozen Mallet for some tankyness and to make it even harder for squishies to get away from you. Since it gives you a nice chunk of HP, I'll then get an Atma's Impaler to increase my damage at my defenses. At this point, if you got the Heart of Gold, you can sell it and fill it's spot in your inventory with a Banshee's Veil. Upgrade your The Brutalizer to Youmuu's Ghostblade and you can then sell Wriggle's Lantern for Black Cleaver to maximize your armor penetration and for a bit of bonus attack speed. Games will rarely reach the point where you'll actually finish all these items, however.

Other balanced item choices:
Wit's End - I used to get this right after Wriggle's Lantern and Mercury's Treads. It gives you a nice attack speed bonus, thus making your passive proc more often and it also gives you some magic damage in addition to your high phyisical damage.

Madred's Bloodrazor - It's a good item to get if the other team goes on an HP stacking frenzy, but it's not really your job to build this item. Let your AD carry get it. It works well with him though, since the bonus attack speed goes well on him.

Bloodthirster - Good to take as a last item if you want some lifesteal and higher damage. You can replace Black Cleaver with this item.

Last Whisper - If somehow you're facing a team that has 3 tanks or something, totally take this instead of Black Cleaver. Flat armor penetration won't really scratch an enemy team that consists of 5 dudes with over 250 armor.

Warmog's Armor - Saintvicious of CLG uses the infamous Atmogs build when he plays Nocturne. I'm not a fan of it myself, since it's easily countered by Madred's Bloodrazor and Kog'Maw. Seriously, every time I build Atmogs on ANY champion, there's a Kog'Maw on the other team and I only notice AFTER I build my Warmog's Armor. Be careful when approaching this build. You can replace Frozen Mallet with it, but I'd personally rather have the slow from Mallet.

Randuin's Omen - Also a good item for Nocturne. Good active, and it makes it easier for him to easily take down enemy carries with high attack speed such as Tristana.

His jungling route is pretty versatile. I usually start at the small golem camp, skip the lizard buff and then just go for a full clear. You can also start at blue buff, although I find it more comfortable to start at the small golems. After a full clear you'll want to gank as much as possible to put pressure on the lanes. Make your enemies pee their pants when you ult. Also, the second blue buff and all the ones that follow go to your AP carry. No buts, no exceptions. He needs it more than you do.

Also, Nocturne is a fairly good counter jungler since he is a good duelist and can take on 1v1 pretty much any other enemy jungler. Exceptions may be the really tanky ones such as Udyr and Trundle.

Another very important aspect of jungling, which my friends consider I'm obsessed with is dragon control. You'll want to get dragon every time it's up. Keep it warded at all times. With a Wriggle's Lantern you can solo it at around level 7. Keep an eye out for enemy ganks though, call your team to help you take it down faster.

In the same vein, you'll want to keep Baron warded at all times also. Nocturne is absolutely epic at stealing baron kills from right under the enemy's nose. Just ult in, smite the Baron, pop ghost and your shield and RUN LIKE HELL. RUN LIKE A SISSY LITTLE GIRL. Then just come back with your team and RAPE THEM SO HARD THEY'LL WISH THEY WERE NEVER BORN. Ah, sorry. I get overzealous at times. Anyway, you get the point.

As I mentioned earlier, as Nocturne, your main roles are assassin and initiator. In teamfights, you'll want to go straight for the enemy carry, pop Youmuu's Ghostblade's active and kill him as fast as possible. When you do this, the enemy team will focus you like mad, hence the tanky build. While they're busy with you, your team comes in and you kill anything you can get your hands on. After you quickly take out their carry, for the rest of the teamfight, you're basically a tank. So fear the most disruptive target, shield any incoming CC and wreck as much havoc as possible.

That's pretty much it. Please vote and leave a comment detailing what you like/dislike about my build. I have had great success with it so far and believe me, I have tried tons of builds for Nocturne. I've been maining him since the day he came out. I find this is his best roles, and I've noticed a lot of top ELO players think the same. I shall soon provide screenshots and videos to compliment this guide, especially of jungle paths and teamfight behavior. I'll also provide some commentary for them, so you can better understand.

Thank you for reading :).