Talon. He's new. He's good. This almost makes up for Riot's first attempt at Skarner. The key reasons to pick Talon on a team are:

• Your team needs an AD "carry"
• Your team could benefit from AoE damage
• You want to play an assassin
• To interrupt channeled spells (enemy Nunu / Kat / Malzahar / etc)

Incidentally, this is my first guide.. and I play a large variety of champions. If it's well received, I will work on creating more guides (next up will be Rammus). I'm new to the concept of making guides, and I do believe in instructional videos, however it takes a lot of time to create them (at least with my lack of knowledge on the subject), so we'll see if it's a worthwhile endeavor.

To begin, for the vast majority of "dps" champions, you always take flash. No exception. Secondly, you have the option of ghost, for more tactical advantage, or exhaust which not only can be used for escape, but also for offense, and in team fights. Ghost, in my opinion, is a greedy person's summoner spell (unless taken in place of Flash, of course).

As for the runes, you definitely want armor penetration marks / quints (although I've read some unverified arguments that a mix of armor penetration and flat AD actually maximizes damage early game with minimal difference in late-game, so I won't claim this is the only way). Cooldown reduction to make his poke and follow-through more persistent would also be highly useful. Haven't been able to try this out, as I don't have any!

Masteries are pretty standard. No surprises there (I hope), although realistically, he could do even better with less points in offense (why do I get increased critical damage when I don't build him as a critical hero?), and more points in defense. You're squishy, living is good.

The skilling order is just what works for me personally. You could very well take Cutthroat before Noxian diplomacy, but you definitely want to maximize your rake first. Rake should be your most used skill, hands down.

When it comes to items, you will need either a lot of mana regen. or a lot of mana. Also, since all of Talon's skills scale with AD, you want as much of that as you can. Lastly, his passive gives you 10% increased damage against cc'd targets, so picking up a Phage or Frozen Hammer along the way won't hurt one bit (Frozen Hammer is a must-have if you need more durability in a particular game). Similarly, some cooldown reduction items, or, if your team is doing very well, some snowball items would also work.

Just to clarify my terms, the laning phase consists of either the part of the game up until a tower in your lane is destroyed, or until 2/3 of a team is roaming (like, for example, if the enemies' two towers in other lanes are destroyed). Basically, if you fear extending at any point after about level 8, the laning phase is over. I've included a video (with commentary) showcasing an example lane phase, for your viewing pleasure:
Play Video
The video should be pretty self-explanatory (particularly because it features an explanation). Long story short, harass, kill as soon as you can, pretty basic stuff. Starting with a Doran's shield really makes the difference in sustainability. If you know before hand you will be laning against scrubs or squishy champions who pose no threat, feel free to start with a blade, or even one of your core items + pots. Again, exercise judgement.

One of the most important aspects of playing the game is staying alive. Talon's ult, with its incredibly short recharge (made even more obscene by buying CDR items), is a fantastic tool to allow you to survive almost any situation. Never be stingy with your ults, but always make conscious decisions when you decide to use them. The following video is meant to showcase just how powerful of an escape mechanism this ult is:
Play Video
Two things to keep in mind from a survival standpoint:

• Your rake slows down enemies, smart-cast it behind you when trying to get away to slow down pursuers. Keep in mind that this will stop you for a few seconds, so be smart in your decision to use it.
• You can use your Cutthroat ability to jump to an enemy creep (assuming the enemy creep is in the direction you are trying to escape to). Similarly, you can use this same tactic for offense, using Cutthroat instead of Flash to get close enough to the enemy for a Rake.

I've upload another video showcasing some Talon mechanics / mistakes in relation to group fights, also narrated:
Play Video
Some key points to keep in mind when fighting as Talon:

• When using your ult offensively, you deal the most damage if you activate/deactivate it while next to an enemy (because more of the blades will pass through them).
• Your Rake's slowdown activates your passive, giving you 10% increased damage. Use your ultimate after your Rake for an immediate damage boost.
• Use your Cutthroat not only for chasing, but for interrupting important spells. Shutting down Kat's ult with a simple skill will help your team infinitely more than you chasing down someone at low health.

I once read a Rammus guide that claimed you have to build him by filling up your inventory with small pieces of larger objects, and build the final versions as the game goes on. This works very well with a variety of champions, and since then, I've stopped trying to "rush" particular items (with the exception of a few carries), and I buy the best available item each time I go back to shop.

Keep in mind that, you should never follow a strict item build for any champ. You should react not only to the enemies that you face, but to their skill level. In higher ranked play, this isn't a real issue, and you can more or less expect every champion to perform, making the calculation of item importance somewhat easier. In general, with Talon, you want:

• Mana regen. Talon is fantastic at harassing, as long as he has the mana to cast his spells. Eleisa's Miracle works great for this. It gives you a reason to get a Philosopher's stone (which also helps your health regen!) early in the game, which is always nice.
• Attack damage. Talon is an AD champ, and 3/4 of his skills scale (fairly well) with AD. You want this.
• Cooldown reduction. I don't focus cooldown reduction in my builds, but this is a highly important quality. Every single one of his skills are great, casting them more often is a godsend. Keep in mind though, his skills have a relatively low recharge.. cooldown reduction is not a necessity, it only makes him more fun to play. I throw in a little CDR using The Brutalizer.
• Attack speed. This isn't crucially important, but since he is an auto-attacker, you need to try to scale your attack speed gradually as your AD goes up. I like to throw in Berzerker's Greaves in my build, unless the team has a lot of cc / AP, in which case I go with the standard Merc Treads.
• Like any good assassin, armor reduction / penetration is fantastic for taking out the squishy carries fast. Black Cleaver is the choice here, unless the enemy is full of tanks, in which case % armor reduction is more effective than flat armor reduction.

All in all, build him how you like, and play well. Just don't do something silly like rush an Infinity's Edge and end up being mana-dry after your combos with no ability to poke.

Cheers.