Ok, I'll keep this part brief, as no doubt you're frantically looking for tips on how to play Nocturne before the game starts, alt-tabbing during the loading screen and speed reading the build guides, maybe even this introduction if you're got the time. Don't worry, that's what all the good players do. So here's the gist of it:

• You're a melee DPS assassin. The idea is to hit hard and fast.
• Jungling works...but it's probably better to lane as you have enough damage output to easily pick up first blood.
• You are squishy, don't be reckless.
• Don't take the middle lane. Chances are you'll lane against a Teemo and he'll spend the entire game hiding behind minions and planting mushrooms. You need to find (and kill) cocky champions to pick up those early feeds.
• You're not Tryndamere, however, so you can't rely on life-steal/refusal to die to keep you alive as you tear your opponents' faces off. So use your abilities!
• ALWAYS use Duskbringer in a fight, even if you don't hit them with it just make sure you stay in the pool. Because everyone likes an extra 60 attack damage.
• As well, ALWAYS use Unspeakable Horror in a fight. You get an extra 200+ magic damage on your opponent and a fear after 2 seconds. It's also a great chase tool. Tasty huh?
• Your Shroud of Darkness is your best friend. Use him lots, and you will feel like such a badass as you block that Crystal Arrow. ALWAYS use it in a fight.
• In case you haven't noticed, you really rely on your abilities. So ALWAYS USE THEM!
• Oh, and Duskbringer is also great for taking down towers. I've taken down towers at level 2 with it. little tip there.

So above I gave a brief synopsis on how to play Nocturne, however seeing as you're still reading you're either

a) One of those creeps who reads these things in their spare time or
b) Someone in the game you're waiting to start has a rubber band powered pc

But that's ok, because I don't mind imparting some more wisdom! So, lets look at runes, masteries and summoner spell eh?

As you can see, our runes are made to complement DPS (mostly). We have attack speed, more attack speed, crit damage and...manna per 5?
Yes. manna per 5.
"WTF?" you may be saying. Well, this is because Nocturne gets rid of manna like it's going out of style. Around level 4, a simple combo of Shroud of Darkness, Unspeakable Horror and Duskbringer will leave you with about a quarter of you manna. Not cool eh? This is why I get the mp/5 runes on pretty much all my characters (unless, of course, they don't use manna) because manna is good, and having plenty of it all the time is even better.

Now, as for the masteries. This mostly goes without saying. Physical DPS = full offensive masteries. Chuck in some armor for a bit of hardiness and, once again, manna regen and you're good to go.

And finally, the summoner spells. This is mainly a matter of opinion, but I always think it best to have an offensive spell and a defensive/escape spell. So therefore I would recommend one of the following:

Offensive
Not only is it a great finisher (especially early game), it's also very useful against champions who rely on heals (either from life-steal, spell vamp or abilities). Many a Teemo have I killed by simply popping ignite on him first, then watching him panic over the sudden lack of life-steal survivability as I slice him into ribbons...glorious...

This is a great spell too; it can be used offensively or offensively.

Prey getting away? Exhaust.
You've become the prey? Exhaust.
Sion just popped his ult while you were trying to disembowel him via his skull? Exhaust.

It really is great, is it not?

Defensive
This is probably the better escape tool. Simply jump over a wall and you should be fine in most cases. As well, if you've been dominating for most of the game you can use it to pull off some spectacular skills. the only downside is the long cooldown, but not everything can be perfect.

Yeah yeah, I said it was offensive before. But I said it was defensive too didn't I? Grab this and ignite if you're feeling lucky.


Ok, so those are those are the spells I'd recommend. Yeah, ok, I only gave you 3 didn't I? Well if you think you can do otherwise then go ahead, I won't stop you.
..Unless you pick one of these:

No

Why would you take ghost if you have Duskbringer?! Put it back.

On some champions, yes. On this one, you're waisting your time. Save it for when you play a support champion.

Now when exactly is this going to help you? If you manage to finish this build you'll have 2 Phantom Dancers, a Youmuu's Ghostblade active and Duskbringer. You can easily move across the map at this point with your insane amount of movement speed, heck you could even race a powerballing Ramus and win. And then lets not forget the fantastic offensive teleport function of Paranoia...

You're not a tank.

It's not completely useless...but only by a little...just don't.

Ok, now that I've hopefully talked some sense into you, lets move on to items. Yay!

So, we start by essentially building into damage, then supplementing attack speed later on. Why? Because 1 point in Shroud of Darkness and a pair of Berserker's Greaves will put you at about 1 attack per second. At level 3. Not bad huh? So, let's begin!

Game start

Grab yourself a Long Sword and a Health Potion. Not much to add to this.

Your first recall

HOPEFULLY you recalled with enough money to buy a pair of Berserker's Greaves. Easy enough with first blood and some minion farming.

And then after that...

As soon as you can turn that Long Sword into The Brutalizer. Why? Because 25 attack damage is always nice, but we're mainly in it for the armor penetration and the sweet sweet cooldown reduction. If you can, also buy yourself and Avarice Blade

Ok, now lets hold up for a minute here.
If you looked at the item sequence, you're probably thinking "Why do you buy the Avarice Blade, then wait ages to turn it into a Ghostblade?"
Simple, more gold.
In case you hadn't noticed this is not a cheap build. You're going to need that extra 5 gold every 10. Besides, gold is good, you like gold don't you? Hold off on the Ghostblade until we have Bloodthirster and a Zeal.
Speaking of,

Once you have 1850 gold...

Recall. Go and guy a B. F. Sword. Bought that bad boy? Goooodd. Now we can really bring the pain. You'd be surprised at how much of a difference this makes to your damage output. Afterwards farm up the rest so you can turn that into Bloodthirster as soon as you can. Then farm some more for a Zeal/tasty stacks on The Bloodthrister

In the event of the game not ending by now

Turn that there Zeal into a Phantom Dancer. Afterwards, power farm. Farm like you've never farmed before. Get Pentakills, kill carries, solo the black dragon 3 times over, commit absolute genocide on enemy minions. Why? Because if you can get yourself an Infinity Edge, then they will know exactly what fear is (which is ironic because you're a nightmare)

If they're persistent buggers who don't know when to quit

Get yourself another Phantom Dancer. Now we have 100% crit chance, near max attack speed without using the Youmuu's Ghostblade active and some very handy move speed. They won't stand a chance against that.

If the game hasn't ended by now, well...I really don't know...

Deviations from this build

Now, not all games suit the same build, so here are some other items that you could chose to replace the Infinity Edge & second Phantom Dancer with.

Bloodthirster & Bloodthirster again
This will give you an INSANE amount of damage and lifesteal, but your crits won't be as often nor will your attack speed be as quick. But you will also be a lot more durable from all that phat life steal...

Black Cleaver
+ 55% attack speed, some damage and some armor shred. Not bad really, good against small-time tanks.

Last Whisper
Got so much armor on the other team it's like versing a regiment of Panzers? Get this, and laugh at their foolish attempts at survival. You attack speed will be lacking if you swap this for a Phantom Dancer but you'll be doing a lot more damage on them now

Madred's Bloodrazor
This does work...so long as they have a fair deal of health and not so much magic resist. This would work well with the Last Whisper against a tank team, due to the attack speed increase and the extra armor.

[This will be a section on play style, in which I'll add a video. Watch this space!]

Some people seem to think Nocturne is a jungler. I disagree.
Yes, he does have the capability to jungle, but that doesn't mean he should. With Duskbringer and auto attacks alone I have picked up plenty of first kills, and you can too. So why would you go kill some Golems for 120 gold, when you can have a Master Yi for 400?

In saying that, don't pick the middle lane.
I've made the mistake of doing so many times, and it has denied me of those vital early feeds. Generally when champions go middle, they're cautious. You don't want cautious, you want foolish. It's quite hard to pick up kills when that LeBlanc keeps hightailing it back to the tower whenever you glance at her. So just take a side lane, you'll find it much easier.