Cho'Gath, unlike most tanks, has the benefit of having descent damage without building any powerful damage items. I use this to my advantage when choosing my builds by building super tanky to the point where i am impenetrable to any outside damage while keeping my team alive with well placed ruptures. In this guide i will show you the ropes of this devastating force that is Cho'Gath and you will learn how to tank accordingly.

These are the runes i use, they may be subject to change based on your play style

Mark: Magic Pen. = more penetration early game to kinda ease the lack of ap, no other good red runes to really replace these with in my opinion.

Seal: Health/18 = Scales well with your Feast stacks allowing you to be extra meaty late game. You could also take Armor Glyphs or even Mp5 if you think your mana regen would be a problem

Glyph: CD Flat = here is where you have many good choices, you can go CD/18, AP flat, AP/18, or Magic resist. I choose cd flat because you are able focus on early feasts on minions to boost your stacks earlier.

Quint: Health Flat = i choose these so that your early game is a bit easier on you, Also good choices would be armor, magic resist, or cooldowns if you dont think you will reach randuins before the end game.

I use a 0-21-9 build so that i can be tanky yet have some exp gain, improved ghost and cleanse.
Some people choose to do 9-21-0 which isnt bad but that means your replacing ghost with either ignite/exhaust. Having ghost helps with chasing or initiating fights while cleanse helps you get outta any cc that would prevent you from landing a rupture or feast.

I start with the Sapphire Crystal so that I will have sufficient mana at the start for ruptures, also builds into your Catalyst for early game lane stay or your Glacial Shroud which is a very nice item to complete early for its nice cooldown and amazing item it builds into.

Mercury Treads are a good item to build next limiting incoming CC that could otherwise break a fight for you. If opposing team does not have very much CC go with Swift Boots, or Ninja Tabi against melee heavy teams.

Building towards your Glacial Shroud or Catalyst if you didnt get it before glacial shroud, is a good choice here so that you will still be able to use it for its passive in lane phase/mid game. Building this into a Banshees is a good choice but if they are not CC heavy or have few casters taking Rod of Ages here would not be a bad idea either. Between Banshees and Glacial Shroud you now have a reasonable amount of mitigation to go with your abundance of HP you have earned.

Finishing Frozen Heart here is always a good choice, but if they have alot of stuns/casters finishing banshees would be more efficient. Either way they will both be finished before getting your Guardian Angel, which is a good way to protect your feasts and also makes your team fear you even more.

Game almost ending sometimes you will reach your 5th item, here i go with either a Force of Nature or Randuins Omen, getting the other if it gets to be a really long game. Determining which one to get is again based on the opposing team.

if you have all above items you will be nearly unkillable and a force to be reckoned with tanking your team to victory.

Level 1-5:
getting your rupture first is always a good plan as it is an easy way to setup early kills if paired with another CC ability, sion, taric, pantheon and so on. Rupture was updated in a recent patch to not scale mana cost with level so this is an easy reason to max it first upgrading to a very nice amount of damage even without ap scaling. Max this first always.

Vorpal Spikes are another good spell this will be 2nd priority to rupture skilling this at level 2. level 3 increasing your rupture damage is a good idea as by now you should have the enemy well harassed or backed to their turret. getting feral scream at level 4 is a good idea as this can break channels or keep enemies from flashing out of your rupture. this makes for your ultimate combo. at level 6 you will be getting your amazing Feast ability. this skill not only does true damage but also if landed as a last hit gives you bonus health that can stack up to 6 times making you even more tanky. the combo of rupture/feral scream/ feast with auto attacks with vorpal spikes behind them can be very devastating to the enemy carries and will keep them from getting too close to you.

I get Ghost/Cleanse, there are many spells that work well with Cho'gath but i find these to be most useful. other great spells would be ignite, exhaust, fortify, flash, teleport.

ghost - used for chasing down carries that are low for the finishing blow, getting to your team mates that got into a bad situation, getting to a tower that is in trouble

cleanse - easily break out of CC heavy teams to score a kill that would otherwise be unattainable, escape from bad initiated fights before bad things happen.

Ignite - because sometimes your combo just isnt quite enough, lowering hp regen/healing to 50% against heal heavy teams.

exhaust - Protect carries by exhausting the enemy that is targeting them, prevent enemies from escape, lower overall damage enemy puts out.

Fortify - save turrets that would otherwise be lost, help out team mates that are fighting on allied turrets.

flash - easy to land combo if able to flash into their face, epic Flash-Nom's, Escaping ganks.

teleport - saving yourself time after buying/dying, help out team mates by getting to their right when your needed most.

Pros:
High Natural Health
Hard to Kill
Good amount of Crowd Control
Great farming capabilities
Hard hitting combo

Cons:
Has to refrain from dying so that he doesn't lose stacks
Not the greatest initiator despite being a tank
non spammable skills

Cho'Gath is a tanky/dps champion but played this way brings out his full potential as a tank. He will be able to soak damage and dish out quite a bit as well. This build does require good team mates to help carry the load as he does not have any way of taunting the enemy, you will be relying on being ahead of the team and being that big target that you are they will most likely start hitting you. Using your size as a psychological advantage can sometimes be overwhelming to enemies as a huge alien tramples all over their team.