This is my first time ever making a guide.

Cho'Gath is an interesting champion. The reason for this is because of his R. His R allows him to gain health and grow in size. Scary right? Most of the time he is used as a tank primarily. However, this build is for AP Cho'Gath. Dont worry! you wont be squishy. RoA and Rylai's makes sure that you have enough hp even if you dont have 6 stacks.

If your put solo top be aggressive! your Q and E will hurt tons!

There is a place between dimensions, between worlds. To some it is known as the Outside, to others it is the Unknown. To those that truly know, however, it is called the Void. Despite its name, the Void is not an empty place, but rather the home of unspeakable things - horrors not meant for minds of men. Cho'Gath is a creature born of the Void, a thing whose true nature is so awful most will not speak its name. Its fellows have been poking at the walls that divide dimensions for a crack, a way into Runeterra, where they can visit their own personal paradise of horror upon the world. They are called the Voidborn, creatures so ancient and terrible that they have been removed from history altogether. It is rumored that the Voidborn command vast armies of unspeakable creatures on other worlds, that they were once driven from Runeterra by powerful magic lost to antiquity.

If such tales are true, then the rumors that follow must be equally true - that one day, the Voidborn will return. Even now, something dark stirs in Icathia, perverting the summoning rituals of the League to allow the presence of Cho'Gath. It is an alien creature of malice and violence, a thing that causes all but the most stalwart to cringe in fear. Cho'Gath even appears to feed on its predations, growing and swelling as it gorges itself. Worse yet, the creature is intelligent, perhaps greatly so, making most wonder how such a monster could be contained. Fortunately, the power of the League's summoning has confined Cho'Gath's presence exclusively to the League of Legends. It is here that summoners use Cho'Gath's Voidborn abilities to help decide the fate of Runeterra. The Terror of the Void knows what fate it would choose for Runeterra, given half the chance.

Woe betide the day when Cho'Gath grows weary of the League.

Okay! Runes are essential and the biggest issue for Cho is Ranged. You can switch AP Glyphs with AP Resist Glyph. Depends with your play style.

I honestly believe the last item is entirely up to you and who your facing against. If you find your team fights are long get Will of the Ancients. E counts as AP attacks and will count as spell vamp. The littlest amount of extra HP helps a long way. If there are tons of CC and you find yourself initiating a fight just because of your Q and your team is scared to initiate on their own get Zhonya's Hourglass and dont forget to use its active after you Q and E.

I mean the stomp hurts, but so does the scream. Its entirely up to you what you want to max first. Q requires thinking ahead but it will help so much and be the biggest poke of your 2 skills because of the range and AoE for farming minions.

When Q'ing an Enemy Champ use E right as they go in the air. This is possibly the best combo for cho and will take down an enemy champs HP a Considerable amount.

R is fantastic being scaled with your AP. It counts as true damage if i can remember correctly. True Damage or not by the end of your match you can find yourself taking over 1k hp of an enemy champ with 1 nom alone.

Use of Rupture and Feral Scream can lead to mana starvation, but if partnered with a champion such as Soraka or one with a Mana Manipulator, using both skills early can yield positive results.

This problem can be easily taken away with conserving mana and with RoA.By conserving mana. This doesnt mean rarely use your skill sets. Just try to have around 100 mana at all times incase of being ganked, sure final kill, or for feasting minions.

If you're having difficultly feasting upon champions, try eating minions until you're larger.

Using Rupture on creeps in combination with Carnivore is a good way to gain health and mana.

Ignite helps with getting the enemy champ just below your R's max damage for a succesful kill plus an addition to your stack.

Flash gets you right in their face if you want to do your nom and also for that reach.

Ghost alternative of Flash. Again depends on your play style.