Hi guys ...
Read this before continuing
This is a Tank based Cho Gath soif somebody is looking for high ability power and burst damage... sorry this is not the build for you

Lets start with runes...
Marks : Magic resist
Seals : Armor
Glyphs : Ability Power
Quits : Ability Power
These are really good for early game Cho Gath cause they will provide you with tank stats as well as a good bit of ability power. Youcan change the ability power runes for health, which i dont have thats why i got AP.

I believe this is the only way to go with Solo Top Cho Gath. Improved Ghost and Exhaust ( Dont take if you dont use these spells ) , 21 points on defense and all the mana regen you need with 8 points at utility.

Starting Items :

Dorans Ring : If you choose to take ability power on runes... Extra Ap and mana regen is pretty good.

Regrowth Pendant : When you choose to go more tanky with health runes... This will build in to a Philosopher Stone.

Dorans Shield : When your up against to champions... Nothing to say here.

Different Builds i use :

Full Tank Cho Gath :
-Regrowth Pendant
-Mercury Treads
-Catalyst the Protector
-Glacial Shroud
-Banshees Veil
-Frozen Heart
-Guardian Angel
-Force of Nature
-Thorn Mail

Tanky AP Cho Gath:
-Dorans Ring
-Mercury Treads ( Your a tank you need tenacity )
-Rod of Ages ( Really good early game stats )
-Frozen Heart ( Armor Stats and CDR )
-Abysal Scepter ( Good AP and MR stats but also great passive )
-Banshees Veil ( Health, Mana , MR and great passive )
-Rabadons ( Great Ap stats )

Other good items :
-Shurelias Riverie ( Its always good to have some extra move speed )
-Randuins Omen ( Really great item against and Physical Damage based team )
on the ap build :
-Ionian or Sorceres? ( yea why not. if the other team doesnt have CC magic pen and CDR work perfectly on and Tanky AP Cho )
-Zhonyas Hourglass ( Great item for baiting teams to focus you...This could easily win you a team fight )

I take exhaust ghost mostly but other spellare good on him too...

Teleport : Well you are solo top so teleport is always good. Especially when your against two champions.

Flash : This spell is great for any champion.

Clarity : Only if youthink that you can her*** the one that is solo top... You will need extra mana to do that so...