Welcome to my first build. This build is really successful for 2v1 laning thanks to Cho'Gath's passive. Cho'gath is an amazing tank thanks to the health bonus of his ulti. Please tell me how this build is after testing it out. Btw, I have only tried this build in normal games. To be honest, the starting of this build was from playing games against the Cho'gath bot in Co-op vs. AL mode. :P This build is mainly focused on tanking as Cho'Gath.

Pros

-Rupture is good at harassing
-Amazing CC
-Feast does true damage, good for killing squishies early levels
-Amazing tank late game
-Good at farming with rupture and feral scream
-Good at escaping
-2v1 is very easy thanks to passive

Cons

-Hard to get kills late game
-Slow at taking down turrets
-Feast stacks take a while to get back, be sure to have all 6 stacks late game.

- Best starting item for Cho'Gath, allows your rupture to harass a lot more early game.

Aegis of legion only if you think it'll help you. If not, try going for some other item more helpful depending on their team, or you can go for rod of ages or rylai's crystal scepter for a little more dmg. But I suggest you stick with a tanking build.

Get a sunfire cape only if they have 2 or more ad/2 or more melee fighters.

Cho'Gath can easily be fed early game as long as you know how to rupture enemies properly. Just use rupture then feral scream to harass. When your hp is about half way gone, or your out of mana, just practice last hitting minons. It's pretty easy thanks to vorpal spikes. If your minions are at their turret and the enemy is low on hp, try getting a rupture on them, feral scream it if needed then feast, and walk into their side of the jungle. Yes, I've successfully turret dived and killed people by their turret and living with a lot of my health still left. Be smart about it.

I'm lazy to write more, just remember your a tank and a good harasser. Late game, stack all 6 feasts asap, and keep in mind how much dmg your feast does. It's true dmg.