I had to paint in the last games in my match history because it was too long to get in a single view. I added the last two games (Swain and Ali) to support the two builds I have on Mobafire for those two Champs.

http://i1193.photobucket.com/albums/aa341/pelikins/cho.jpg

Just another game I happened to have a screeny of, so I figured why not...you can see my itemization in this one, though the game didn't last long...
Notice the creep farm scores. Farming creeps early means farming players later. This is why we take offensive masteries...

I feel like Cho is one of the most under rated and powerful champions in LoL. I feel like many Cho players, however, gimp themselves willingly through poor itemization, mastery selection, and runing. If willing, lend an ear and read through this guide and more importantly, try it before you knock it!

This Cho carries, this Cho anti-carries, this Cho aoe dps's, this Cho tanks, this Cho does everything, but he still can't dance.

Here is the general theory behind the build:

Have you ever heard the phrase "A good offense is the best defense"? Well it's quite literal with Cho.
As you may be aware, Cho has an amazing passive. Every time Cho lands a killing blow to a creep or player he regenerates a % of his max hp and mana.

This means a Cho that can effectively kill creeps early game, can not be harrassed as he heals every time he kills a creep. In addition, he gets mana returned with every kill allowing him to cast more spells, more dead creeps, more hp. On top of this, his spells are all AOE. This means that a well played Cho can harrass and kill creeps in a single spell, all the while being returned hp mitigating incoming harrassment and, of course, every time you kill something, you get gold which allows you to buy equipment to kill more creeps, get greater hp/mp pools and do more damage to do everything listed above more affectively.

Farming in this manner, you then are able to buy gear to improve your offensive capability to heal more to harrass more and to get more gold. Effectively snowballing your champion down the road to victory.

In addition: Cho's skills allow him to do massive amounts of damage in aoe and to any one opponent. Since the single target damage is pure, a Cho with this build can single out an enemy and kill it within a few seconds, even if it is heavily supported by its teammates.
While Cho's slurry of AoE skills spread damage around to soften up multiple opponents to give you multiple focus target options.

General:

This Cho is an AP hybrid build. It has amazing damage capabilities and survivability. I would classify this build as an off tank build, but I have tanked successfully with it in ranked play. It works best to 2v1 or solo or to lane with a stunner (especially eve). Descriptions of the best playstyles are listed below- depending on the scenario.

Skills:

Rupture- Cho's bread and butter. An AoE of spikes shoot up from underground damaging enemies, tossing them into the air, and slowing them for a duration after landing. This skill has a decent range, does incredible damage, and allows you to close on enemies. It is a great farming tool, and your main harass. Make sure to keep it at max level.
Pro Tip: When aiming at players make sure to place the AoE where the player is headed instead of where he is. Aiming the AoE directly behind the enemy is a best bet as the player will hear the sound before seeing the graphic and their first instinct is often to get away from you.

Vorpal Spikes- Perhaps the most underrated ability in the game. Cho's auto attacks shoot spikes in a cone infront of him damaging enemies for a base amount plus a % of his AP. NO COST! Fantastic for farming, jungling, and harassing. Secondary skill to level.

Feral Scream- Cho damages enemies in a cone infront of him. Any enemies hit by this skill are also silenced for a duration. Great for the silence early one, also good damage in team fights later on and for farming around level 5-7 when rupture leaves creeps at a sliver of hp.
Take one level of this early and then level it last.

Feast: Nom Nom Nom! - Cho "eats" an enemy doing massive pure damage (ignores resistance) to a player or approximately double to a creep. If Feast kills the enemy Cho recieves a buff which increases his max hp by a set amount stacking 6 times. It is very important to get Feast stacks x6 up on Cho asap. Unless you have an opponent in a position where it is likely you will be able to kill him, it is suggested that you feast mobs while laning to get 6 stacks for the first team fights. Cho loses 3 stacks on death so don't die!

Summoner Skills:

Exhaust: exhaust is a fantastic summoner skill for Cho as he needs to get into melee range in order to use two of is abilities. Exhaust will save you from auto attack life steal champions, and will make it easier to land rupture on a mobile target. Cripple also decreases the target's magic resistance by an additional 10 and increases the duration by .5 sec.

Flash: Talented players will not allow you to get within melee range when within feast range. Flash makes it possible. Also good for escaping and getting a rupture to land when otherwise would not.

Masteries:

Defensive masteries- with the offensive caster splash.

Runes:

Seals: HP per level. These will compliment the FoN and Thornmail purchases.
Glyphs: straight CDR for farming ease, getting feast stacks faster ect.
Magic pen quints and marks: magic pen stacks great for damage.

Ok so many people will look at this and say "Cho has pure damage in his ult so magic pen isn't going to help that at all." This is true, however, you are going to cast rupture, feral scream, and use vorpal spikes 15 times (100 times for VS) before you use feast again. Not to mention you want to buff your AoE damage as much as possible as it will be hitting multiple enemies where feast only hits one. So lets not be naive in thinking magic pen is not good for Cho.

Itemization Explanation:

Start with a Doran's Ring. This will boost rupture's damage, give extra mana to rupture more often, and give extra hp so that everytime you get a killing blow you get increased hp return.

I then go for boots. CDR boots will help significantly for farming and stacking up the ult buff.

Next work on getting a Catalyst. This will increase your hp/mp pools significantly and thus the returns you get when killing a creep. When you get this item, you should be able to manage one spell (rupture) per creep wave and still stay max mana. This is about perfect as lvl 4 rupture will leave the ranged creeps with just a sliver of hp (one or 2 vorpal spikes should finish them, or you can feral scream them down) and lvl 5 rupture will kill them in one shot.

At lvl 6 grab your Feast ability. Make sure to use it whenever it is off cd. The hp boost is significant and when compounded with you passive you will be able to ignore much of the harass people thrown your way. If you have a laning partner, lvl 6 is a great time to get an easy kill as Feast's damage is tremendous.

Next, upgrade your catalyst to a RoA. The RoA is incredible for Cho. It will boost your hp to a point where you are nearly unkillable, especially because the ap on the rod will give you potential to kill so many creeps. The mana will give you extra mana return on killing blows to cast more spells and do it all over again.

By now you should have 6 ult stacks and your Rod at least partially charged.

Since you have a large health pool it is now important to stack armor and magic resistance. Getting a negatron cloak and a chain armor will effectively increase your survivability substantially for a small price. If the opposition lacks a damage type skip the corresponding defensive item and go to the next step.

I now get a deathcap to significantly improve my damage.

Nashor's Tooth was seemingly designed for AP hybrid Cho. It is perfectly itemized to boost Cho's damage capability. 50% AS will make you a considerable melee threat with lvl 5 vorpal spikes. 25% CDR will help rebuild Feast stacks if you do happen to die, and will make you a huge monster (oh wait...) in team fights due to your aoe damage capability.

Adding a Force of Nature is perfect for regening your massive amount of hp. The movement speed increase will help you close on enemies and the MR will help survivability considerably.

I next buy a sunfire cloak. I perfer the cloak as it works well with the FoN and I rarely issues against melee so I don't need that much armor. Often I will substitute in a thornmail here if the opposing team's physical carry is an auto attacker. Ashe's will kill themselves if they attempt to attack me with a thornmail.


Game strategy:

Late game play strategy is pretty simple. Rupture as often as you can on the other team and utterly destroy the first person dumb enough to come close to you. So I'm not going to talk about it in detail. Instead I'm going to focus on early game strategy.

3 Scenarios come to mind.

2v1: This is by far the most challenging scenario (especially against double stun). Most opponents won't be able to zone you due to the tremendous range on rupture and self healing capability. I like to rush into the closest bush before they can get there (stay in the back part of the bush). That way you know what is in your lane and if they plan on zoning before they can see you. If they go into your bush land a rupture on them as they enter and retreat. Then, go in with your creeps and check the bushes just in font of the last melee creep. If they are setting up a gank in the bushes the creeps will help you fight them back. With rupture, an exhaust, and ignite along with creep support you can force them to retreat. Pop your heal potion as needed. This will also force your creeps to attack them instead of the enemy creeps. This means that your creeps will lose the creep battle and their creeps will push toward your tower where you are safe. Play conservatively, focus on creep kills as they heal your hp. Once you get lvl 6 stack up your ult on creeps and still focus on farming gold, stacks and levels while avoiding as much harass as possible.

1v1: This is very easy as Cho. Your self healing will mitigate most of the enemy's harass. If they venture into creeps ruture on them (pathing is harder in creeps to avoid the rupture and you get creep kills and harass at the same time doing this.
If they don't go into creep waves focus on creep kills. If they try to zone you, avoid his nukes but don't be afraid to get hit by minor damage like occasional melee's as your self healing will take care of it while your creeps will turn and hit him and he most likely wont be able to self heal as well. Additionally, him harassing may force him to run out of mana which will be a huge advantage around lvl 6 when your damage ramps substantially.

2v2: Try to lane with a stunner who doesn't normaly creep often. Eve is an excellent choice. Try to close on the enemy before stunning/slowing them to maximize the dps potential of the stun lock duration. Then have the teammate stun/slow the target before using rupture to insure a hit. If you plan a gank at lvl 2-3 grab feral scream lvl 2 instead of vorpal spikes.
If the opponent has a good escape ability use exhaust right before your opponent uses an ability on them for the debuff/ damage increase during the stunlock duration.

Always focus on creep killing to self heal and get mana return.

Team Fighting:
Cho fits perfectly in distanced harass teams. His rupture is fantastic for guerilla warfare style teams. Keeping a distance and supporting team harass is a great way to go if your team comp suports the play style.
He also is great in the burst out of the woods and gank style team fight. Rupture/Feral Scream are great initiation abilities which can really give an early edge in a team fight. Then close on a low hp target and ult him immediately (remember once you have 6 stacks you get nothing from killing it so use feast on first kill targets right off the go when blitzing). Taking out an enemy this way will give you one more warm body than they have, which is often all you need. If you hit multiple enemies with rupture and fs the other team gets to start the engagement slowed silenced and at 60% hp which screams death.

You are all such insignificant creatures...