Hello, this is my first build I didnt know how to start so... I will tell you that I'm looking forward what you will say and what can I do to improve this build. I played Xin lots of game got 4 Penta Kills with him and I most tell you he amazing DPS champ not better as Pantheon because Xin goes for attack speed and DMG as Pantheon goes for full DMG. I hope you enjoy it and get good stats with my build :)

As you saw in the item order I get 3 main Damage items; IE (Infinity Edge), The Bloodthister (great for his stacks if your not dying a lot) and The Black Clever. The Black Clever is now a great item as it gives you not only Damage but Attack Speed. However, if opposite team has good DPS champs as well you should be considering buying a Frozen Mallet so that you want be squishy.

I go with Armor Penetration runes and Seal+Glyph runes for Critical Chance you might be thinking why Critical Chance ? The answer is simple it gives you 8% to get a critical attack at the start of the game which is great.

Why don't you get attack speed runes ?
I didn't get attack speed runes as they will give you around 7-10% of attack speed and Xin's attack speed is already amazing, his W gives him passive of 35% attack speed and when you active it gives you even more ! so there was no use.

I heard that Xin was a TANK not a DPS!
I saw maany builds which told people to go as a Tank not a DPS. Its true that Xin makes a great semi-tank like Warwick. But, still is not like Rammus or Garen. You need to go as a DMG for Xin not a tank !!

Pros

-Great attack speed
-Great ulti for teamfights
-Good laner
-AMAZING AGAINST SQUISHY !!

Cons

-Low HP
-Small Armor/Magic Resist
-Low at mana

Well I'm using a only one combo with Xin which is Q+W after E with R straight away. But, remember not to waste so much mana as Xin is really low and has small regen. with it.

Use your Q to cancel ulti's like Absolute Zero (nunu) or even Idol of Durand (Galio) those ultis are great as nunu's ulti slows you and Galio's taunt you.