Now i have been playing Nocturne since he came out and i must say i have been getting positive results every game, he is hella fun and clears minions waves in moments.
Now i dont jungle on Haunter because i think its boring, thats just my opinion, i prefer to dominate a lane with a skilled partner.

now bla bla bla etc etc. try b4 you buy. (dont rate down because you disagree with an item, try it before you rate it)

These runes are simply the rune i use for all my melee and tank champs, they are universally good. gives alot more survivability. Although i am guessing that there are much better runes for noct out there.

Standard layout for melee dps masteries, however i havent gone into the defensive tree for obvious reasons. Improved ghost + teleport + the increased buff duration, see once i get my wriggles i often head out into the jungle.

I build items in this order! this includes all the items not listed above

Wriggles is ****ing golden for this champ!
Jungling becomes a breeze, once i have this item and boots im unstoppable, i clear out the jungle and in most games i freakin dominate the dragon every time it spawns, this is a huge advantage for your team.
However one of the best things about it is the free wards, now these wards in combination with teleport is amazing!
so many games, ill just pop a ward in the bush in my lane, go back, buy, the other team pushes a little bit and BAM i teleport behind them where they have no escape; easy double kill.

Attack speed boots, pretty simple, the attack speed early helps, i spose these could be replaced, i havent tried anything else yet.

Youmuu's Ghostblade: HOLY ****! this just ices the cake! The biggest thing for most people is remembering to use it, if you buy this item you must learn to use every chance you get, its amazing, use it on dragon, buffs and most importantly on other players.

Zeal / Phantom: pretty simple, once you get these you have the run speed and the crit which carry you to victory.

Trinity Force: Now i had a quick squiz over the other Nocturne builds and i see alot of hate towards this item, now i do see the rason, but i dont get this item every game, it is indeed situational. I will get this game if the opposing team mostly comprises of squishies. It really helps in chopping them up.

The other option to trinity force is;
Madreds Bloodrazor: Get this item if you're facing a tanky opposition, combined with the 2.5 attack speed i acheive with the build it really cuts them down to size.

Bloodthirster: Simple enough, gives the damage boost + the much needed lifesteal, i have gotten this item every game, very reliable.

Now that is generally all the offencive items i get, but it can change from game to game.

Defencive items, i'm not going to go in depth with these, its simple, if they have lots of casters grab a banshees veil, lots of melee; a thornmail, need health? grab a warmogs. Its not to difficult.

In most cases its open with Q followed by E then shield yourself with W, this order can change at any times though depending on the champ, you might not even need W or you might need to use it b4 you even get to the champ.

Now;
Nocturnes Ultimate: Hell i would be happy to play this champion even if he didnt have this awsome ult. Nocturne is fun as he is but then with this bad boy thrown in its.. hell i cant even think of a word.

When to use the ult:

You see someone with a ward or they are foolishly pushing a lane by themselves
The enemy team is getting cocky, maybe one or two of them pushing a turret and no teamates are available, pop this first phase of this ult and they will open run back to their turret like little *****es.
In a teamfight in which the other team is slightly separated
Ganks
While running away, shielding enemies view can make an escape much easier if you're crossing through a lane or if you only have 1 enemy that is close to you.
There are probly heaps more, ive only been playing him for a few days, im sure other people have fuond some nifty tricks.

I don't want to go into these, there are obviously many alternatives but these work very well.

Ghost: Great for running / chase
Teleport: this is what i find makes this champ so much more fun.

Take this scenario: Your team has just been aced and the other team lost 4 members, they have a xin zhao that is just about to push your middle turret, you teleport to a ward you have near the dragon, then ult off to mid, scoring an easy kill. This is very unexpected because he still thinks he has alot of time and you are back at the well.

Alot of people have been getting ignite, to be honost i see ignite as an insurance for those people who get away on like 20hp and for the reduced healing. But if you dont waste your ult you can easily snag those people who just manage to get away, if you're buying wards you can see where they are heading and jump in their face.

Man.. this is like typing and essay, what was i thinking...
hmm... one this i forgot, with this build its really easy to solo baron, make sure you use your shield to stop the decreased dmg buff and get the attack speed buff.

Yeah.. this dude is ulta fun and i own the ice skin ( which is ****ing bad ***! ) and yeah he is an overall fun carry assasin.

Below is a screenshot i just took ( not the best because i wasnt planning on making this guide i'm just waiting for a friend to get out of his game ) and yeah it shows the potential of this build. Btw my deaths are so high because im a psycho xD. Ill work on not dying now and upload a better screenshot.

wait dw, i dont know how to add an image.
Peace!