Welcome to my Xin Zhao guide.

The name of this guide was inspired by Xin Zhao's story - he had to fight 300 soldiers - alone. Many times more than the previous record. So why that name in this build? Because this build will allow you to stay on a lane without having to go back for a long time, not even after you have fought 300... minions :D

I picked armor penetration, cooldown reduction and attack damage.
In the beginning, Xin Zhao will have a lot of attack speed, but what's attack speed when not backed by some attack damage? By increasing attack damage, and having great attack speed; you'll be able to attack a lot of times, and for each time you attack with an attack damage addition, the damage is multiplied with each hit, meaning, Xin Zhao will be able to deal one huge mass of damage. And armor penetration makes the damage even greater. Plus, with Vampiric Scepter which I made teh first purchase for this build, it increases your survival rate. It really is so useful early in the game... you have no idea.
Cooldown reduction. It is true that Xin Zhao has Battle Cry for that purpose, but it will not reduce the cooldowns as much as you'd want it to, no matter what, you'll stay useless for a certain amount of time, which these runes will reduce.

Not much to say here. I'm playing Xin Zhao aggressively, so the 21 ones are, of course, on the Attack masteries. The rest are on Utility. So both of your Summoner spells, Ghost and Exhaust are getting buffed, you'll have great offense, plus you'll gain some more experience.

Now this is the key of Xin Zhao's capability of fighting against 300 - the first item you'll buy.

Item #1: Vampiric Scepter.
Basically, this item allows you to stay on a lane longer, and increases your survival rate by you cannot imagine how much. It is true that Xin Zhao's passive ability, Challenge, gives him a certain amount of healing, but the amount is too small to be of any significance. If you feel endangered, drag the foes to your turret, and kill some minions to steal their life. This way, the opponent won't be able to attack easily, your turret is safe, and you regain health, and once you regain enough health (of course, taken that you took some damage already) you can launch a counterattack without fearing death; and you can rinse and repeat this how many times you want. Another good thing about this item is that you don't need Health Potion at all.

Iten #2: Berserker's Greaves
You need boots; everyone needs boots. But what boots? I chose those that give you attack speed. If you somehow manage to get forced to base earlier, buy the Dagger first, and later upgrade it to these boots. To me, a good Xin Zhao is a Xin Zhao that becomes fast fast.

Item #3: Zeal
Item #4: B. F. Sword
Actually I'd go for a B. F. Sword before Zeal, so if you can afford it, go for the sword. The thing is, you'll have a very nice amount of attack speed thanks to Battle Cry by now, and you only need more attack speed for later levels. If you go to base earlier and you can't afford B. F. Sword, then get Zeal.

Item #5: Phantom Dancer
Now that we have a very nice amount of attack power, it's time to beef up the attack speed a bit further, getting some crits while in the process, and as a great bonus, your movement speed is increased by a very nice amount. The more times you attack, the more the B. F. Sword boost pays off, don't forget.

Item #6: Bloodthirster
Now to make use of those Vampiric Scepter and B. F. Sword; upgrade them to this beast. With such great attack damage and speed, you'll be able to steal quite an amount of life too, increasing your survivability by far.

Item #7: Youmuu's Ghostblade
Attack damage, critical, cooldown reduction, armor penetration, and a nice attack speed buff upon activation, plus you gain some extra gold from Avarice Blade until you fuse it. So when you activate this and Battle Cry, your attack speed becomes 220% of what it usually is. And it even gives you some movement speed to help you chase a fleeing foe. The only question is when to get this item, and my choice is this. After Phantom Dancer which gives you enough speed to utilize its active, and after B. F. Sword or Bloodthirster so you have some nice damage behind it.

Item #8: Black Cleaver
The more the game goes on, the more power you need; speed as well. More power and more speed equals MUCH more damage, so why not? Its armor reduction also helps, of course.

Item #9: Infinity Edge
Of course, you don't buy this in one go, go for B. F. Sword first if you can, if not, then Pickaxe. This is only an icing on the cake, you should already be pwning; but what's better to finish off this build with than a huge attack damage and crit rate?

So, a bit about Xin Zhao's skills.

Passive skill: Challenge
Gives you some minor healing. Not enough imo, but when combined with Vampiric Scepter it does make you live longer.

Q skill: Three Talon Strike
Skill I max out after Battle Cry. The more attack speed you have, the more likely you are to knock the foe into the air, so attack speed is essential for this skill to work; of course, it's not as useful until you get some attack power. But after you get a B. F. Sword you'll be around the level when you start focusing on leveling this skill up, so the timing matches perfectly. I get this at level 3 simply to have it for knocking up the foe; once I have more attack damage, the more useful this skill gets; that's the time for leveling it up.

W skill: Battle Cry
Level up whenever you can. At level 5, it gives you a HUGE attack speed, plus, you can double the attack speed boost by activating it, so basically, your attack speed becomes 170%; it lasts 7 seconds, good enough to kill someone. The earlier you gain LV5 with this skill, the faster you'll pwn. Remember that you have the Vampiric Scepter from the beginning; so yeah, the more times you strike, the more damage you do, meaning, the more you'll heal, and the less likely it is that you'll lose a battle. It is this build's code.

E skill: Audacious Charge
Unlike Xin Zhao's other skills, this one uses ability power. So basically, you only use this skill for what it does, not for damage. And what it does? It gets you closer to the opponent, and does some damage in the process - and slows the target, making it harder for the foe to escape, and easier for you to kill it. That's how this guy rolls; slow, then kill. For this build I gave this skill the least priority; I want to do some major damage, which this skill won't do. However, for Level 1, it's great. The damage it does can mean first blood when laning with someone who can strike the foe consecutively with you right after you charge. Don't forget Exhaust to enable that.

R skill: Crescent Sweep
It's simple: Audacious Charge the foe, then strike them with this; it takes a HUUUUGE chunk of health from the foe; and if you keep the foe close long enough - it's a certain kill. Excellent against tanks. Useful for killing huge amounts of minions on one spot too.

Exhaust is the perfect spell when you want to finish someone off, making them unable to escape. If that is not enough, there's Ghost as a backup plan, which means, Xin Zhao can chase one target without fail until he kills it. A good alternative is Flash instead of Ghost. It's a matter of preference, actually. Being faster continuously with Ghost has helped me survive more times than Flash did, though. It is also good for running back towards the turret when you have to, to stay alive and continue killing minions, stealing their life and preparing counterattack. Ignite is also a good option to replace Ghost; maybe that damage you deal will be what you need to finish off that escaping foe rather than chasing it. But it doesn't work that easily most of the time.

Just one simple thing to say here. Xin Zhao works excellently well with a stunner/snarer, who will prevent the foe's movement, giving you more time to spam your auto-attack backed with huge attack speed, and increasing the chance of Three Talon Strike to succeed in knocking the foe up. And he also works great with Blitzcrank, since he can pull the target to you, getting it close to you even without Audacious Charge, which you then use when the foe starts running away and manages to make some distance between you.

Pros:
-excellent attack speed
-foe can't escape, at least not that easily
-survivability and long lasting on the lane
-great movement speed
-great turret killer
-not too squishy
-eats super-minions for dinner, enabling a comeback after a destroyed inhibitor
-easy to play even for beginners

Cons:
-Gets focused often
-Doesn't have good escape methods ( Ghost can help though)
-Rangers can be bothersome for him, especially those with some attack damage and attack speed

Thank you for taking your time reading my guide. I honestly hope you'll find it useful.