Cho'Gath has always been one of my favorites since the early stages of me playing this game. He is really fun to build, too, if you do it right. As you can probably gather from the title of the build, I play Cho'Gath as an AP Tank. I make full use of as many Magic Penetration and AP boost items as I possibly can, such as Void Staff and Rabadon's Deathcap. Cho'Gath's AP can easily reach 300 and beyond, especially with the 30% boost that Rabadon's gives it. Especially with Rupture and Feral Scream, this can give Cho'Gath the edge he needs in battle to flatten his opponents.

Being I'm only level 19 at the time of creating this build, I really don't use runes all that much. However, I would use Greater Quintessence of Swiftness, Greater Mark of Insight, Greater Seal of Potency, and Greater Glyph of Celerity when I got the IP for them.

I've done Cho'Gath's masteries all the way up to what I would do for level 30 as soon as I got to it. As stated earlier, I am only level 19. My main focus for Cho'Gath is offense. The only reason I use one point in Utility is for Ghost, and I'll explain that in the Summoner Spells section.

I always start with Doran's Ring when it comes to my build. Next, being that Cho'Gath relies pretty heavily on his abilities, I buy Ionian Boots of Lucidity for the cooldown reduction. Rylai's Crystal Scepter comes after that because of Vorpal Spikes, allowing Cho'Gath to slow every hit. I build Rod of Ages next for the Mana boost, since Cho'Gath is so ability heavy. Abyssal Scepter comes after this for the Magic Resistance, since Cho'Gath tends to be pretty MR squishy. After this, I get Void Staff for the Magic Penetration. Rabadon's Deathcap finishes out my build.

I try to master Rupture first, because that seems to be my big damage dealer (other than Feast, obviously). Feral Scream follows, but I get Vorpal Spikes second, and then Feral Scream. Vorpal Spikes really adds that extra damage early game, and can be nasty once Rylai's is applied to it.

I usually use Ghost and Exhaust in tandem with each other. I usually Exhaust them first just to slow them down, and if it's not working enough, I'll Ghost so I can still keep up with the enemy Champion I'm trying to kill.

My only problem with Cho'Gath is that he tends to be rather squishy, especially early game. Once I start cranking out my build, however, Armor tends to not be a problem. MR is a different story. Come up against a Soraka, Annie, or the like, and you are in for a rough battle. This is where Abyssal Scepter comes in handy.

MR squishiness aside, Cho'Gath makes an excellent tank. I'm not saying my build is the best one and everyone should use it, but I hope this at least gives you some ideas. This is personally my favorite to build, and it helps me out with the way I play. I tend to be a more balls-to-the-wall player, and I'm very agressive with my melee characters, especially Rammus and Cho'Gath. Enjoy my build, I hope you like it, and GL HF DD DS.