This is my first build based on a champion that truly inspired me. The champion I'm talking about is of course everyone's favorite eternal nightmare: Nocturne. My first game with Nocturne I went classic Jungling(I will add a build for this later). However my most successful games have been with a lane-based Nocturne as he can get many creep kills with his passive alone as well as harass out of lane or to death. Nocturne has a long distance skillshot that works as a harass, chase and escape! He is also one of the few champions blessed with a fear, the most annoying of all crowd controls(Very practical and makes the enemy look foolish A++). On top of that he has a built in Banshee's Veil that, if used correctly, can effectively save you from being nuked or stunned!

I feel it's always a good idea to start with pros and cons as it gives people a quick way to fit the build to the enemy team.

Pros
-Excellent Ganker
-Great Farmer
-Great Harass
-Great Chase
-Rare and Practical Crowd control
-Fairly good Jungler
-Abilities have good chemistry
-All skills have multiple uses
-Don't pretend he doesn't turn you on.

Cons
-Squishy
-Low mana pool
-Vulnerable to CC
-Needs some practice to be good with
-Still quite buggy(It can be expected)

I go with
Greater Mark of Desolation x9
Greater Glyph of Clarity x9
Greater Seal of Alacrity x9
Greater Quintessence of Desolation x2
Greater Quintessence of Fortitude x1

Because:
-Armor penetration is good for any DPS/Assassin
-He has a weak mana pool and needs mana regen for mid game ganks
-More Attack speed early on helps get more creep kills and can allow you to use you're passive more often
-Armor Penetration never hurt anybody... except it did.
-A little bonus health at level 1 can drastically increase your laning capability

Substitutions:
-You shouldn't be substituting these out for anything.
-If you don't feel you need the mana regen, or would rather have it earlier on you can go with Greater Glyph of Replenishment. If you plain don't want mana regen I'd suggest Greater Glyph of Focus for CDR since you won't be building youmuu's :(
-I really like these seals. However, you could go dodge if you have trouble with rival carries, not really recommended Fear should take care of it.
-You could just go solid x3 Desolation or x3 Fortify if you like those better. If you have a personal preference that isn't those two I can't personally torment your mind so feel free.

I go with these masteries because he is an AD/DPS and it's always good to get 21/0/9 because you simply don't need more than 21 in a single zone. All of my suggestions are pretty self explanatory but I would like to offer up some alternatives.

20/0/10:
Throw the extra point from Havoc into Utility Mastery. It can be more viable in ranked games when everyone isn't screwing around.( Blue Buff Is Very Good )

Jungle 21/0/9
Throw your points into Offensive Mastery and Plentiful bounty, you can sacrifice sorcery unless that's your preference.

Now this will take a while so I'll return to give a long explanation later, for now Let me just give up some alternatives and how I start my game.

First I buy a dagger and Health Potion.

I lane until I have about 1,100 gold then I return to buy my Zeal and a pair of boots.(this should not take long, just last hit with your passive) If you're doing incredibly well I recommend you begin building Wriggle's.

From here you should start ganking once or twice, even if it's on your own lane, that's how cool you are!

After a successful gank go back and buy/finish Wriggle's

Return to your lane, you will likely be a little behind because you ganked, unless it went really well then that's just fantastic I'm so happy for you.

Basically Build your Zeal into a Phantom Dancer then rush your BF sword.

Pretty much do whatever you want from here but I suggest getting banshee's before late game.

Yay! Turns out I decided to go test my jungle build so this guide is under construction!
I'd like to not be rated on my laziness so unless you are just really really angry at me then go ahead click on that generic Thumbs Down! If the build works for you? I really can't do anything about that either but don't be mean, everyone knows noobs only click on the guides that have: A) A Punny name B) A High Success rate.

but srsbsns:
Jungle Guide + Route coming soon
In-depth Item Explanation coming soon
Skill Sequence/Summoner Spells Coming Soon!
Less Coming Soon and more Chapters, Coming Soon!

Wow I'm such a funny guy. ;)