First than all, my english is not really good, so sorry about that, but i think i can make you understand me, if you got any correction to do, you'r welcome to do it.
Second, this is my first guide, so sorry about the desorder, but i think you will be able to understand and you will be glad to take that fat Vayne down in 1 second.
Now, this guide is completely about taking the enemy carrys with almost 90% success, you can even take 2 if you got a good position in battle, and if you can go away alive, that's just a bonus gift. Taking off the glass canon fast is all you are going to focus on.

PROS:
-Great gap closer to blow up that fed carry.
-WAY TOO BIG focused nuke and burst.
- Shadow Assault can finish them off and it can even let you get away if you deal enough damage.
-DRAGONBLADE TALON.

CONS:
- Squishy as a fly, do a wrong move and you are dead.
- Hard to master, he got a lot of combos and ways to use the skills, so it can take time to learn how to play him.
- He's better at mid, so it means that your team needs to supply the ap that you are not taking.

MARKS AND QUINTS

I take 9 +1.66 armor pen and 3 +3.33 armor pen for some obvious reasons, armor pen is made to make physical damage to the enemies, and even more to champions, flat ad works better for minions (in ad carrys for the last hit, etc), so i'm taking all the armor pen i can get to insta-kill that anoying guy killing my teammates.
SEALS Geting mana regen allows you to harras like a boss the early game with Rake so this is a good kind of rune for talon, since seals are more likely a defensive rune, and we dont care too much about that (remember, if u want to survive a 3 vs 1 or making a easy penta, you are playing the wrong champ, you must have a tunel red vision on 1 guy)
GLYPHS

flat cdr glyphs to be able to kill enemies more often.

I think this explains by itself, 21-9-0, but maybe you are asking yourself, why not 21-0-9? The reason is simple, your target is not always alone and waiting to get killed, you need a little bit of endurance to be able to reach him and to drop your full combo. Then you can get away to keep fighting from behind or die in peace if you get focused after that. Your items helps you with that too but we will talk about that now.

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You can start both ways, Boots and 3 Health Potion or doran blade, but i recomend the first one, because you need the movement speed to harass with Rake, and the early sustain from Health Potion.




After that get The Brutalizer, this items is made for Talon, good early ad, armor penetration and cooldown reduction. All works really good on you.



Then B.F. sword will help you to rise your base damage in all your skills dramatically but you are not going to complete it yet.



Now you will get Last Whisper to increase even more your armor pen and to increase a good amount of damage. They are going to take armor soon or later if you are doing good, so we will need this, and it helps a lot early and late game.




Now finish your boots, Ionian boots are the best option for Talon, since he's highly skills dependent.




And then get Infinity Edge to increase your AD again and Noxian Diplomacy will deal a good amount of damage with those crits, youmumu's crit chance + Infinity Edge's crit chance + Trinity Force's crit chance will give you a good % of crit on your .


Now you will finish youmumu's blade to increase more all the stats you will need, and the active is pretty good, because when you waste all your skills you cant do anything until the cds goes off, so you can active youmumu and deal a good amount of damage to another champion (your target will be alredy dead)


Trinty force will help you with the crit chance for your Q, Hp, AD, and that sheen's passive with Noxian Diplomacy

You need this 2 summoner spells, Flash will help you to get in range to blink with cutthroat and release your full combo, or to get away in case you didnt had to waste Flash, and Ignite will do damage per sec with the bleeding of Noxian Diplomacy to finish them off in case all your burst wasnt enough.

When you are in the lane in lvl, you will harrass with Rake until you get the level 4, and try to save mana before you get the it, so when u got rake lvl 2, cutthroat lvl 1 and noxian diplomacy lvl 1, you will blink to the enemy, autoatack with noxian diplomacy and use rake to finish the harass combo. This way you will take a close amount to half the enemy's hp. When your skills are up again, you will repeat this combo, but this time you will chase the enemy and use ignite. 80% of the times it ends in you getting a FIRST BLOOD.

Now, your full assassin's combo is: E to get in ---> Q ---> W ---> R Now pay attention here, if you kill him opening your ring with R, dont close it and run while you'r invisible, but if you didnt kill him, close the ring autoatacking 2 times and use ignite. That's most likely a sure kill.
Here's a video courtesy of VFV Rasmül when you can see what i'm talking about. Play Video

You can use the talon's skills of a lot of ways, the most common are:
- Jump on a minion with cutthroat and use Rake to harrass/kill a target that's too much far from you.
- Use Shadow Assault before blinking into your target. This alows you to be invisible before geting in and be even more hard to stop. (do this only when your target is a really hard to catch kitty, because you are losing the damage from the opening of Shadow Assault)
- Noxian Diplomacy resets your autoatack count, so to maximize your damage autoatack and right after use Q to do a double atack.

-LET THE TANK INITATE, you must not lead, you will wait till the fight start to get in position and executing the enemy carry.
-Be always in the shadow, dont show yourself till the fight begins, if it's possible be near of the enemy carry to kill him as soon as you can.
-GET ORACLES, even if you'r not a tank, you dont want them to know where you are, if u appear from nowhere, it will be to late to save that poor Corki.

Thanks to all for reading my guide, i will edit it to improve as much as i can, and if you can help me with any tip, or recomendation, please do it, any criticism is welcome.
Have fun and remember, be a true assassin.