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 betides the day when Cho'Gath grows weary of the League."

Try to get someone who hits hard as a lane partners, because of your stun, slow and silence. Ex. Master Yi ( Does alot of damage with Alpha strike, Wuju style and Double Strike ), LeBlanc ( Sigil, Distortion does a lot of damage )

You can use Rupture to harass, because its pretty spammable. When you get Feast try to go for a kill. Finish target with Feast.
After that you want to A) Get stacks to feast by jungling/creeps B) Gank. Remember to secure lanes when they are in trouble.

In fights try to get as many as you can get the hit from Rupture and Feral Scream. They are doing pretty good damage. Use Feast to finish enemies, because you get stacks from it. After you have full stacks you can use Feast as a high damage nuke and let teammates score kills.

And ofcourse, Learn to lead.

Starting item: Doran's Ring
Boots > ( Health Potions and Mana Potion]] ) > Ruby Crystal > Sapphire Crystal > Boots of Swiftness > Catalyst the protector > Blasting Wand > Rod of Ages > Blasting Wand > Abyssal Mask > Glacial Shroud ( Chain Vest first ) > Frozen Heart > Guardian Angel > Rabadon's Deathcap or Zhonya's Hourglass ( I prefer Deathcap to be more terrifying ) > Elixirs

Also, Remember wards!

Sell Doran's Ring when you feel so.

Good

Ghost: Escaping, Chasing, Getting from A to B. Very useful.

Ignite: Does very nice true damage.

Exhaust: Very good damage reduction and slow. ( Change Deadliness to Cripple if you take that )

Teleport: Suprise ganks to wards, Getting from A to B fast. Defending turrets.

Cleanse: Get rid of those stuns!

Flash: Escape, Chasing.

Heal: Only if you are a bad laner


Bad


Smite: You are not jungling

Fortify: Let support get this.

Rally: Just bad

Revive: Even worse. ( And you have GA )

Clairvoyance: Let support get that too

Clarity: You should't be running out of mana

I dont have these runes. I put runes that I think are best for this build.

Greater Mark of Magic Penetration: More damage

Greater Seal of Evasion: Yis hate you.

Greater Glyph of Cooldown Reduction: Theses runes + Masteries + Frozen heart ~ 28% CDr.

Greater Quintessence of Health: More survival at lane.