There's allot of great guides about Cho'Gath that covers how you should play Cho, so i will just redirect you to the too best (IMHO)

http://www.mobafire.com/league-of-legends/build/aaahh-godzilla-chogath-activates-limit-break-194883#chapter3

http://www.mobafire.com/league-of-legends/build/gentlemans-guide-to-ap-chogath-top-265137

Why wont you use allot of time introducing the guide and stuff? Because this isn't really a guide, its more a page where I go through the maths behind Cho' and shows why you should use my build (Shown above)

I will however be editing this page once in awhile when I have the time, and who knows, I might make it into a proper guide:)

What's so awesome about Cho'Gath?

Well, Cho'Gath have two skills that makes him EXTREMELY awesome.





So why are those skills so awesome?

Starting with Vorpal Spikes.

Basically, a problem with most AP champs is that once they are on cool down, they have no real defence/way to fight back against the enemy champions. Some champs have ways to counter this, from CC and slows to quick cool downs.
Cho'Gath Have another way to counter this, his Vorpal Spikes increases his already high base damage at level 18 (Second only to Skarner ) with 80, increasing by 30% of your AP. This means that at level 18 you will have a base damage off at least 210 (without no damage/AP increase)
This can increase quite allot, which I will explain later in the Maths section.

And then Cho'Gath's ultimate, Feast.

Well, it scales with AP, and its true damage. This is nice, but its actually the feast stacks that makes cho'gaht dangerous. At full stacks at level 16, he gets 900 HP. Nearly a free Warmog's Armor. This allows Cho'Gath to be kind of semi tanky, even without buying HP. I will cover this in the maths section bellow.

Basically, the only two core items are Iceborn Gauntlet and Zhonya's Hourglas. These two items are for armour, AP, awesome ability's and mana.



Best shoes in the game. 25 magic resist, and the awesome 35 tenacity. Cho'Gath is the biggest unit in the game, so you need those shoes for all of those annoying blitz cranks and other CC spells. I upgrade them with Enchantment: Alacrity because cho needs all the speed he can get when he needs to chase down and eat those ****ers.

VS.

This item is Okay-ish. I'm much more into Rod of Ages. Take Rylai's Crystal Scepter if you want Liandry's Torment or are doing good, buy Rod of Ages if you want just about anything else, because its better. But the slow on Rylai's Crystal Scepter is just awesome. It makes chasing down enemies SO easy. Other than that, the slow also triggers Liandry's Torment passive, making it so much more awesome.



Iceborn Gauntlet this is kind of a unique item. It gives armour, AP and mana. All things cho needs to work good. On top of that it haves a great and awesome passive, slowing and damage all around it. The damage isnt that great, but the slow is nice. I have tested it, and it doesn't trigger Liandry's Torment. I usually buy Sapphire Crystal early to help with my mana use.


This is where there is great diversity. Liandry's Torment gives great damage, Warmog's Armor puts your HP to 4500 Abyssal Mask gives you both magic resist and Ap plus and awesome aura that helps your team out, Runic Bulwark gives some of the best survivability, putting your Magic resist at 215 and your armour at 224. Even better it puts your HP to 3938 but takes of 91 of your AP. In my opinion, this is the most viable way to build Cho'Gath as a tank. I have an entire chapter about the Liandry's Torment


Just a plain awesome item. 50 armour, 100 AP and one of the best abilities in the game. This ability can block ultimates that would otherwise kill you such as Nunus ulti. I love their reaction when you just dodged their main nuke:)


It was nerfed in last patch, but the 25% increase is still awesome. A must if you go full (******)AP. If not, a warmog's armour can make you into a freaking god. other armour/hp items would work too.


You can really play around with all of those build, I most say they are all awesome.

The Masteries have been swamped around quite allot.

Its perfectly possible to go up in other trees, but I like to go up the offensive tree... just because it give this small boost with Archmage and the new Spellsword isn't that bad either.

This is my favourite part:) The theory:) I will write it all in plain white, but the conclusion will be in red. This is a beautiful colour.

So, lets start with the HP.

Cho'Gath have 1880 hp at start. + 200 + 500 + 108 +900. 3588 total HP at level 18 (Full stacks)

Then the AP. (80+40+100+70+120+18+6=434)*1.30 (30 cos Archmage + Rabadon's Deathcap) = 564.2 AP

And then Cho'Gath's spells.

Rupture (305+564.2)*1.02 ( Havoc ) = 886.58

Feral Scream (275+394.94(564.2*0.75=423.15)*1.02 ( Havoc ) = 683.3

Vorpal Spikes 80+169.26(564.2*0.30=169.26)*1.02 ( Havoc ) = 254.24

Feast 650+394.94(564.2*0.70=394.94)= 1044.94 TRUE DAMAGE ( Havoc doesn't affect true damage)

That's one hell of a nuke...

Now, the auto attack. I think this is one of the more interesting parts of Cho'Gath.

Taking the above maths for Vorpal Spikes, he deals 249.26 magic damage per hit. if you add hes auto attack (129.7) he gets 249.26+129.7=376.96. Now, the masterie Spellsword gives 5% of your AP in extra magic damage, so 564.2*0.05=28.21+376.96)=405.17*1.02 ( Havoc =413.2. 413 Damage per hit for a mage is pretty darn great. In my experience, this means you can limit those annoying life stealer's, and actually use your auto attack.

And to top it off, we have Iceborn Gauntlet dealing 125% of your base auto attack, (Which happens to be the hardest hitting in the game) so 129.7*1.25=162.3*1.02=165.5+413.2=578.74 damage after each used spell. Me like!

Magic resist:

Cho'Gath Have 52.5 base magic resistance at level 18. He gets 25 from boots, and the runes I have put on him gives him 71.82 I have also given him three points in the Resistance . so 52.5+25+71.82+5= 154.32. This is the base AP build magic resistance, and to be honest, it does the job. If you are against a heavy magic team, switch Rylai's Crystal Scepter for Rod of Ages, and Liandry's Torment for Abyssal Mask. this brings your Magic resist up to 200 and gives you more HP. If it still isn't enough, you can switch out Abyssal Mask for Runic Bulwark. This will give you even more HP and more armour, a nice passive and bring your Magic resist to new heights.

One of the real strong points in this build is, that you can easily make the shown conversion.
You will deall less damage because you loose Liandry's Torment but you will still have the same amount of AP, and 45 more magic resist from Abyssal Mask.

Armour

Cho'Gath have 82 base armour at level 18. he gets 110 armour from items, and 2 from masteries. So 82+2+110=194 or 65% reduction this can further be increased as shown above, to 224 armour.

So you have a nuking mage, with semi strong auto attacks, 200 armour and magic resist, 3500 HP, and did I mention he can hit you for 1050 true damage?

This is a chapter only about this awesome item. Because its awesome!

Liandry's

Liandry's Torment is so awesome on Cho'Gath not because it activates on Feral Scream, Rupture and Feast, but because it activates on Vorpal Spikes!!! Thats right, Vorpal Spikes is one of the few AeO attack sync. spells that takes advantages of Liandry's Torment awesome effect, it also takes advantage of Rylai's Crystal Scepter effect, slowing the targets, which in turn will trigger Liandry's Torment giving double the damage. But the awesomeness doesn't stop here:-D

Liandry's Torment debuff for AeO effect is, that it only last for half the duration (3 seconds) but Vorpal Spikes strikes the target at such a rapid rate, its in effect nearly constantly, eating of 5% (2.5 in Vorpal Spikes case) of the targets current HP. But because we have Rylai's Crystal Scepter the damage is effectively doubled. And because you are steadily hitting the enemy at 0.778 attacks per second, there HP will shrink in no time:)

I will try to update this guide. Its not done, and far from perfect.
If you have any feedback, I would love to feast on em'. All idears for builds would be awesome, cause I think we kind of those right now, after they nerfed the living **** out of x da Reaper's guide.

And again, I urge you to take a look at his guide:

http://www.mobafire.com/league-of-legends/build/aaahh-godzilla-chogath-activates-limit-break-194883