Hello, and welcome to my guide for Cho'Gath! Please, do keep in mind this if my first guide and is not meant to be taken seriously, so I wouldn't reccomend doing this in ranked matches. Anyways, this is a pretty short guide and I will go over the basics, I doubt the spells need any going into. They are as follows:

Runes
Items
Summoner Spells
Pros/Cons
Summary

Here are some youtube videos of what could be the outcome of your builds.)

http://www.youtube.com/watch?v=aLtpJug0_5Q (Warmog's. NOTE: Not complete in this vid.)
http://www.youtube.com/watch?v=esKe1RJjt1s (Rabadons - I am not sure if this is WITH runes or not.)

For the first build I made sure all the runes would supply bonus ability power, and they alone gave at least 100 additional ability power, which is quite a bit considering a lot of spells boost you for around 50% of your ability power. The extra ability power will definitely come in handy early game, as you won't have to mass your skills as much to get the same effect meaning you have to recall less and less early game. Keep in mind the bonus is per level so it will only be about ten-twenty in the first level.

For the second build I made sure they would all provide the most health they could possibly, giving you an additional health, somewhere around ten-thirty in the first level as well, keeping in mind that it will give you a larger boost later game making for of an effect.

For build one I have selected a mass of Rabadon's Deathcaps. This is simply because, if you can get your 900 health with those six stacks, (using the runes as well) you should have around 2600-2800 health which is quite a bit. If you get six Deathcaps and include the passive you will have around 1200 ability power, which will help boost your abilities potential damage into the high hundreds, maybe even thousands. I know from personal experiance with this build that if not fed, you can take out almost half health of someone like Teemo or Twisted Fate using your skills like Rupture or Feast. Your passive should also get an AP boost which is helpful for minion crowd control.

For the second build I have selected six of Warmog's Armor. This will raise your health into the high thousands, and including the passives it can raise your hp to aroiund 9000-11000 (450x6=2700 - 2700+7895= 10595). I have done this too, and know from personal experiance it will take multiple people just to bring you down assuming you have a full build done. If fed, it will take maybe only 3-4 of them to take you down in a considerable amount of time assuming your team is not there. If not, then assume it to be a full team fight and you still living with most of your health if you initiate. Your health regen will also be in the hundreds per 5 seconds. Assuming 200 you will regenerate 40 health per second healing you fully from 0 in about 250 seconds. Which is not that long if you consider healing 10,000 health. Having this much health will make you "unapproachable" or "unbeatable" to most players, even if they outnumber you two or three to one, they might not even want to try initiating on you with that much health.

IMPORTANT: Oracles Elixer
I extremely reccomend you getting this, especially if you are not the fastest person to react or not the best player. You want to start buying this mid game, and hopefully you only need to buy one (it lasts until death). Oracle's Elixer lets you see invisible units and objects. It will come in exterme use if you have an Evelynn, Shaco, Twitch or along the line of a Teemo. It will also let you see the traps like Mushrooms that Teemo can set down, and let you attack it, as well as wards in the jungle.

RECCOMENDED:
Flash Since you will not own any boots (possibly early) and late game it is reccomended you keep a tool that will help you get out if you need to.
GhostThis, like flash is best used for if you want to get out of a battle or catch up to a pest like Teemo trying to get away with his Boots of Mobility.
Exhaust This is just like Ghost, but the opposite. It can deter enemies from a further chase, or let you catch up to enemies in general. It can be used in unison with Ghost for an even greater effect.

Neutral effect:
Teleport It will get you where you need to go, but it's not going to help you if you're being hunted down and you need to get out of there. I would reccomend it for early to mid game, but after that there is not much use for it.
Cleanse This spell with remove all disables such as Fear, Slow, Taunt and Stun. It will become extremely useful in late game, but is not of that much importance early to mid-game depending on who you are up against in lane.

Try to avoid unless you're extremely confident: (Only going over the major ones)
Heal It is more of a crutch than anything, and if you are worried about dying becuase of health, then go for the health build. Heal (at higher levels) can make you seem like a novice player and make you more susceptable to ganks. It's just not any good for you especially late game, with all of your health and mana regen.
Clarity This is, like I said unneeded. I know Cho is a mana pig, but you do not need this if you're going to take the deathcap build. You will be using your spells a stunning lack less in the late game, besides, thats what the Blue Buff is for, isn't it?:)

Pros - Warmogs:
Stunning increase of Sustainability
Decreased need to recall
Great to initiate and take initating spells
A huge distraction letting your squishy characters get more damage in
Huge tank for Baron - Your health rivals that of his own.

Cons - Warmogs
Your damage will be on the lower side, your output won't have as much effect.
Your defense is down quite a considerable amount, and you will be taken down slightly easier.
There are no boots in late game making you someone easy to catch up if you're on CD


Pros - Rabadon's
Huge damage output late game making you able to take out opponents with a few abilities
Exceptional ganks early to mid game depending on how fed you are
Easy to solo dragon than anyone else in the earlier game

Cons - Rabadon's
Your lack of health and armor will make you an off tank, attacking from the behind.
You will still get focused first, and maybe even more now because of the lack of armor
You do not get a boost of Mana Regen from these, so you are still mana hungry early game

Some leaving notes - I am always happy to take some CONSTRUCTIVE critisisms. If you have ways to help me, please go ahead and suggest them! All credits go to me. This guide is not meant to be taken as a joke, more of a thing to do if you feel like it. Feel free to test it out agaist bots or something.