Hello! this is my 1st build so maybe its not the greatest build that you may read here. If something is missing or I forgot something tell me! Dont vote if you dont try it.

Pros
Shield that can save you
Fear for good chasing
Nice ult
Great passive
Can be used for jungle too
Cons
can be killed easy if shield is on cd
Classic skin is garbage

[/list]Umbra blades: Nocturne's passive. You use it every 10 seconds. basic attacks reduce the cooldown by 1 second. Thats why you are getting attack speed items
Duskbringer:The q of nocturne. useful to chase champions, farming and destroy enemy turrets.
Shroud of darkness : The w skill that makes nocturne awesome. you have to use it before someone uses an attack and... BOOM, you have extra attack speed
Unspeakable Horror:
The e skill of nocturne. Nice move cause with this attack you can fear someone and have some time to kill him before he goes back to his turret-base.
Paranoia: FINALLY THE ULTI OF NOCTURNE. Its very useful for ganking it has really long range. your opponents cant see nothing on minimap except near them ONLY. Use it and your opponents will say: ''Oh sh1t nocturne is coming''. you can launch yourself an an enemy champion to deal some damage.

I use: ExhaustGhostgood for escapes and chasing and stacks with duskbringer for better speed
IgniteGood for kills
Clarity

Ok. First start with a Doran's blade.
Then go for the Berserker's greaves.
When you get boots you should be lvl 3-5 and you will need to deal some dmg.
I usually go for a nice Bloodthirster and then farming to make it more effective.
Now you should be lvl 6-7 and with some kills if you doing good.
now you have 3 choices:
1)Go for a Black Cleaver
2)Go for Infinity Edge
3)Go for Phantom Dancer
After you get one of these items go for a Frozen Mallet. it has some hp and some dmg too and a great passive. if you doing bad try to get frozen mallet first. now you should be like 15-17 lvl. If they have some heavy tanks get last whisper.

I get q first and then go for w if they harass you with abilities and you know how to block abilities or else get your e for second ability. get w at level 3. max your q first. your e second and your w last taking ult whenever its possible.

And that is my nocturne build. with this build you should pwn your lane and get tons of kills. and have some time to gank someone with your ult. and that haunting skin is so good