STILL IN PROGRESS

In this section, I will cover and justify the choices of items for this build.

Doran's Ring:
Doran's Ring is by far the best starting item for Cho'Gath. It gives him health, mana regen, mana on kills, and a bit of AP. The only other viable starting options I see are Doran's Shield and The Dark Seal.

Irecommendccomend Doran's Shield if you are truly unsure about the matchup and know that you struggle against lane bullies and only take The Dark Seal if you know you won't need the rest of the mana regen and that you can heavily snowball your lane by killing the enemy laner, making use of the stacking ability of The Dark Seal.

Hextech Revolver
While Hextech Revolver is only a component, I find it necessary to cover. Hextech Revolver, in some cases can be kept and not upgraded until after completing Luden's Echo. Why is this? Hextech Revolver has very strong base stats but also a very strong passive, one that contributes heavily to your burst damage. In a situation where you will be able to weave in auto attacks into trades and all-ins, having the extra burst capability along with the AP from Luden's Echo may aid you in your damage more than getting the health components for the completion of Hextech-Protobelt-01.

Farming is EXTREMELY IMPORTANT on Cho'Gath. Due to his natural passive and that of Doran's Ring, last hitting properly must be one of your main goals, especially in the early game where your mana costs will be very high. Sustaining your mana pool and using spells only when necessary is essential for using Cho'Gath to his full potential.

Your E ability can be used to easily CS minions since it adds magic damage to your next three autos with a relatively low cooldown. NOTE: The magic damage applied towards your E-empowered auto attacks is added AFTER the initial damage from the auto attack itself. This means that if a minion has 100 health and you have 95 AD with your E adding any amount of additional damage there is the possibility that damage by another minion, champion, or another source can be dealt to the attacked minion BEFORE the additional magic damage is dealt.

Along with your very powerful E spell, Both Q and W can both be used to easily clear waves. For the most part a single Q will clear the ranged minions after a few levels and with some AP, with this build. With a Q-W combo you should be able to clear any non-cannon minion wave with just two spells.

Additionally, your ultimate ability, Feast, can be used to secure cannon minions in lane if you are worried about last hitting, giving you another feast stack. Once again remember that only 6 minions or non-epic monsters can be used to gain Feast stacks. After getting 6 stacks from minions or non-epic monsters, any Feast used on these will still deal damage but will not give a Feast stack.

Your goal as an AP Cho'Gath is very simple. Hit your Q and W spells and follow up with your R and E. Your massive AOE knockup and silence will give time for your team to reposition and put down damage on incapacitated opponent champions. Sometimes simply hitting your Q and W on unsuspecting enemy champions can win a teamfight single-handedly.

I would be lying if I said you wouldn't get strange looks and occasionally flamed for playing Cho'Gath in this manner. Due to the recent buffs to the Tank Feast Bot Cho'Gath many summoners believe that the only way to play Cho'Gath is with full tank items. However, long before the time of the buffs to tank Cho'Gath, he was played almost purely in AP or hybrid AP to a great success. However, AP Cho'Gath has also received buffs with the reduced cooldown on Q and the improvement of E. Stick to your guns and be confident in your pick, with this guide you should know what you are doing and will be able to prove all those haters wrong!

This is a fairly simple and standard Rune Page for this build.

HOWEVER, always change your rune page to accommodate your opponent laner and the major damage source of the enemy team.

For example, if the enemy team is Full AP with a Corki ADC, you will want to switch out all of the Seals of Armors for Scaling Health and remove the CDR glyphs in exchange for Flat Magic Resist and Scaling Magic Resist.

Pros:
One of the most naturally tanky champs
Great base damages and great scaling into late game
All basic abilities have strong AOE CC capabilities
Easy to pick up and learn
Only 1350 IP in store

Cons:
Weak early game
Weak against percent hp damage dealers
Mobile champions will make it difficult for you to land your spells