Nocturne is clearly, one of the best assassins in LoL. Due to Duskbringer to move faster, shroud of darkness to cancel ANY spell, including ultimates and Paranoia for a nice good gank.

Pros:
Epic skin
Assassin
Insanely awesome skills and animation
Ganker
Jungler(Sorry my build is a bit more lane friendly)
Cons:
Squishy
Mana starved.
Usually targeted in a gank.

I pick critical chance attack speed due to getting the job done and higher crit chance while you have an Infinitiy Edge. Do to the damage you'll be dealing, and your duskbringer you can pull out a chase or knock a tank out possibly.

The Good
Smite: Great for jungling
Teleport: Decent if warping across the map or to a tower.
Fortify: This skill is great in the early levels for saving turrets and killing heroes who are trying to kill your ally. You might have to be observant when using this.
Heal: A great skill always. Could trick a low hp enemy to attack you at low hp. Pop the heal up use your ulti and finish them off.
Flash: If you need to juke or catch up to your enemies pop this baby up. Great for escapes and ganks.
The bad
Clarify: I wouldn't get this due to other items you can get.
Clairvoyance: You definetely do not need this one due to your ulti.
Ignite: Depending on your enemies. Personally You do not go AP or have the mastery for +10 ap so I would not.
Rally and Revive: Wasteless. Do not bother.
Cleanse: You aren't a tank or would need due to having many escape options. Possibly but a no for me.

Madrid's Bloodrazor is always a great item. If they are building tanks I'd recommend it definetely for jungling and for tankers on the opposing team
Trinity force is an excellent item even though the price is a bit much, but if you want more hp and stats nocturne needs go for it.

I would NOT recommend ANY AP items! The only Item you might need that is decent for nocturne might be Archangel's staff due to low mana.

Sword of occult- Always a great option if you are going to gank and offensive. Personally didn't put it in the build due to New players.

Last Whisper- Last whisper is a great option if they are having tanks and stacking up armor.

All in all Nocturne is an amazing champion. A great ganker, escape artist, and dpser. He may is a well made character. He is not a great farmer, but his ganking and skills make up for it. He is also a great jungler. (This is my first build so please comment and rate so I can do better)

The End!

[/color]