Hi, thanks for reading if you have come here :)
I will now explain why this build is the best build.

The reason why I prioritise Eclipse so much over Youmuu's Ghostblade is due to the armour penetration. Lethality is good on Talon but is bad at the moment overall, especially since lethality becomes a useless stat as soon as the enemies start building armour, so you could be full lethality build at 30 minutes and snowballing, but if there is a tank top lane and he reaches 2-3 armour items, you will tickle him at most. Armour pen on the other hand scales.
With Eclipse giving you 4% armour pen per legendary you will have around 76% armour pen when full build when going:

Eclipse Prowler's Claw Serylda's Grudge Black Cleaver Guardian Angel


because Black Cleaver and Grudge give 60% armour pen alone and you also have the mythic passive from Eclipse and some lethality from it as well as Prowler's Claw.
Now why go Prowler's Claw when I say lethality is bad? Prowler's is currently a staple item on Talon, because of its passive and when you reach your two-item power spike the one-shot potential skyrockets. If you use this to get a lead and finish your build it doesn't matter that you don't have lethality as you one-shot any squishy anyways as well as having great value against tanks. Even if you can't one-shot the the tanks, you can play more like Bruiser Talon and kite between your passive procs and easily 1v1 them.

Now, the runes are easy to explain.
Personally, I go with the Domination tree and Electrocute in nearly all games, unless they have 3+ melee tanks, then I go Conqueror as you will not be looking to one-shot squishies as much and it is better for extended fights and skirmishes.

Sudden Impact is probably one of the best runes you can take on Talon as you activate it in nearly every fight, nearly every game I deal 2,000+ dmg just with this rune.

Eyeball Collection gives you more AD

Now for the last rune in the domination tree it becomes a bit more difficult.

I prefer Relentless Hunter as with the movement speed you have much more roam potential and it even feels as if you are making up for not having Youmuu's Ghostblade. But Some even go Ingenious Hunter to reduce the cooldown of Eclipse and Prowler's Claw, however I think that this would be better suited with a Conqueror rune page and a Bruiser Talon build. And finally Treasure Hunter is also picked over Relentless Hunter by some, but since I am looking to snowball and I have good farm and already have the free boots I think it is not necessary.

For the secondary tree I always go inspiration for Magical Footwear as you save 300 gold and get more movement speed which = more roam and kill potential.
Always go Minion Dematerializer and use it on the caster minions so you have very fast wave clear and can roam or split effectively early on.

Pros

Strong early
High snowball and carry potential
Very fun to play

Cons

Very weak when behind
Not the best late game

There are many combos for Talon but these are the most essential ones to know:

AA + Noxian Diplomacy + AA
Can be used to proc Electrocute in early fights and burst enemies in your melee range. It can also be used for quickly last hitting minions


Rake + Noxian Diplomacy + AA
Most basic combo to proc your passive Blade's End

Flower oneshot combo
Rake + Noxian Diplomacy + Shadow Assault + AA + Blade's End

This combo is the best oneshot combo and it's known as the 'flower combo'. You can instantly proc your passive with this and oneshot any squishies as long as you are not behind. You W, then immediately Q on to them after pressing W, then you R while you are leaping at them, then immediately basic attack.