Hi guys! This is my first guide, and this one will be fun to play with. If I have any mistake with my grammar, just pardon me because first of all, I am from Asia and I don't speak English very well (in my opinion). This is a FULL AP Xin Zhao build. First came AP Master Yi, then AP Tryndamere. <-- These champions have the ability to carry the game with the unorthodox build, and I also tried if it works with Xin Zhao. (I am going to post successful AP Xin Zhao games soon). So far, this build has been successful in most normal games. Playing this in ranked maybe risky, but if odds turn into your favor, it will then be your victory. Good luck, summoners!

This is my first guide, so I don't know how you guys did those stuff like the other guides have.

Pros:
+Fun
+Great AOE Burst Damage
+Insane Heal in late game
+Great for backdooring and doing solo baron
+Great farming ability
+You don't need mana potions
+Pentakills will be easy

Cons:
-Difficult Early Game
-Slightly difficult to build
-Blue Buff dependent
-CDR dependent
-Hard CCs is a great counter against this build

MARKS (Flat Attack Damage): You need to have a little extra damage to compensate your disadvantage in early game.

SEALS (Flat Armor): You also need more tankyness when you are laning solo top.

GLYPHS (Scaling CDR): These runes will help you a lot during late game. A little CDR won't hurt, right?

QUINTS (Movement Speed): More mobility. :D

We are going to get the usual AP builds, except that there are a few addons.

Offense (27):
-Fury (Attack speed) -> more heal
-Sorcery (CDR) -> Less cooldowns
-Blast (Scaling AP) -> More AP, anyone?
-Destruction (Increased Turret damage) -> For backdooring purposes
-Havoc (Increased Damage Dealt) -> More damage output
-Arcane Knowledge (Magic Pen) -> More penetrating power
-Mental Force (Flat AP) -> AP AP AP AP AP AP
-Archmage (AP Percentage Increase) -> This will support your AP increase with your Rabadon's deathcap
-Exexutioner -> DAMAGE! DEMACIA!

Defense:
NOPE

Utility:
-Wanderer (MS Increase) -> More mobility along with your MS quints.

Early game:
You will go with a normal Xin Zhao build. Boots-potions combo. Do like a normal AD Xin Zhao. Get a Bilgewater Cutlass. Kill. Kill more.

When you finally get a Hextech Gunblade, your gaming phase will change. You will mostly focus on doing ganks on squishy champions, to further help you win.

The reason you will rush Hextech Gunblade is this:
It will be very difficult early game if you start with AP items.
Bilgewater Cutlass is a very good starting item because it gives you decent AD and lifesteal, and is cheap. Furthermore, this item can be upgraded to Gunblade, which will help you start your AP build eventually.

Then you must go for Nashor's tooth, because it gives you AP, excellent Attack Speed for your heal, and Great CDR for your barrage of attacks later on during the game.

After Nashor's Tooth, go for Rabadon's deathcap. This will dramatically increase your AP, and will also dramatically increase the dumbfoundedness of your enemies as you burst them to death.

Next is the Lich Bane. Gives great AP, and its passive synergizes with your E-W-Q combo. Also becomes a semi-nuke along with your high AP.

Lastly, I go for malady. Why taken last? Its hit passive will be not so good early game, because it depends on your AP, and your AP early game is a bit low. If pursued late game, your basic attacks will be a blast even without casting your combo, and the Attack speed bonus is great too. However, a good replacement would be Guinsoo's Rageblade.

[to be continued]