Hey guys, I'm Aham. This is my first guide ever so I'm hoping to not get flamed and I hope this guide works for you guys.
Talon is melee assassin who picks his fights, jumping in and out of battle, and as Phreak says, deals a tonne of damage. So, I've been playing Talon ever since he came out. I saved IP for him because I was psyched since his sneak peek. So, I bought him and I sucked because all I could play back then was Master Yi. But I had a hard time accepting that because I just loved the character so much. So I kept at it, and as I gained more insight into the working of the game itself, I figured out how to play Talon. Once I was good, I wanted to be better. So I tried out different items trying to optimize. And this is where I reached.

Off late I've been seeing a lot of players building attack speed on Talon with items like Phantom Dancer because they feel it puts their AD to better use. Let me say this once,TALON IS NOT A CARRY. Sure, he can carry a team, but that does not make him an auto-attacker.

Oh yeah, building Infinity Edge on him isn't the smartest thing to do either(Scroll to bottom).

Pros:

• Amazing burst damage
• Good overall kit with decent CC in Rake and cutthroat
• Good escape available with low cutthroat and Shadow Assault
• DoT from Noxian Diplomacy

Cons:

• Squishy until late game
• Not a strong farmer/laner/pusher
• Gets focussed
• Mana hungry early game

Runes are pretty standard as most AD champions. You can use Greater Mark of Desolation or Greater Mark of Attack Damage or mix both.
For quints I would suggest Greater Quintessence of Attack Damage as it has better ratios.
You need the Greater Seal of Armor and Greater Glyph pf Warding because you're squishy.

Masteries focus on maximizing Physical Damage output and reducing cooldown. I don't bother with the lifesteal because he's going to gets lots throughout the game and I open with Doran's Blade anyway.
In the defensive mastery tree we do what we can about his squshiness.

I can't say too much here. Suit yourself. Really.
I go for Ignite for securing the kill and Exhaust because as an assassin, you primary job is to shut down the opponent team's carry.

If you're in a duo lane and have the Exhaust/ Ignite combo, you can go in for a first blood right away. Start with Noxian Diplomacy for that. If at level 2 one of your opponents is low and is almost over-extending level up your Cutthroat to go in for the kill. Otherwise, level Rake, it helps you farm.
Of course, you can always choose to start safe and harass by starting with Rake then going Noxian Diplomacy then Cutthroat.
Once at level 3, you can harass with E>Q>W combo. Of course, don't spam it, he IS mana hungry.

I max this first, it is the main source of the damage you dish out. It procs on Sheen and Trinity Force doing IMMENSE damage.

I max this second for the good slow and faster clearing. And yeah, it procs your mercy

cutthroat is your initiator. Damage amplification,silence and situational escape. I say situational because you can only use it if the enemy minions' position works for you.

is your ultimate. It allows you to jump into a teamfight, hit everyone, and then move to that squishy carry hiding behind the rest of his team. And the 40% MS bonus. WOW! Great for getting away, great for getting to your target.

So this is your combo:
E>Q>R>Is your target getting away?>W>Q>Is your target still alive?>Is your E back?(still getting away, otherwise just use Q)> If yes, pop it>If no or this isn't enough> Ignite

Not so hard,eh?

Open up a Doran's Blade and rush Ionian Boots of Lucidity and rush Bloodthirster for good damage and good sustain. If you're doing fine, you'll be doing some decent damage by now

When building Trinity Force, look at what you need then.
Are you too squishy? Build Phage
Having mana issues and really wish your Q would proc? Build Sheen
Everyone's too fast for you(unlikely)? Build Zeal

Next, go for your Hexdrinker which you will build into Maw of Malmortius. Good damage, good sustain from its passive(more damage=more lifesteal) and that spell shield is a life-saver.

Now build your Frozen Mallet. It makes you tanky, it makes you sticky and it procs your mercy. By this point, an additional 10% of your damage will make things pretty damn funny. No seriously, you cant keep Waiting for your cutthroat to come of cooldown in the middle of a fight.

The last spot I usually fill in with another Bloodthirster to become a nightmare for the opposition. Even Guardian Angel is a good idea. If they are stacking armor(they must be by now,right?) then Last Whisper is the obvious choice.

*I don't build Infinity Edge on Talon because he doesn't have the attack speed to justify all that gold spent on those crit stats. Besides, Trinity Force is an AD Caster's Infinity Edge(Bonus 150% AD on next hit=250% damage on crit).

Last Whisper for armor stackers
Guardian Angel for when you're getting focused
Youmuu's Ghostblade mainly for more cooldown reduction, the AD, armor penetration, crit chance and active are all great
zeke's herald for more cooldown reduction, AS, health and lifesteal

Try it out.
Let me know what you think.
Good luck and Happy summoning