Not Updated For Current Season
Note: Yes, I know it's long, that's why I broke it up into question/answer sections. If you have a specific problem with Cho'gath, or don't understand the decision about part of the build, you can find the answers here.
Why Cho'gath?(updated as of release v18.104.22.168)
If you take a look at Elementz's tier list (https://www.leagueoflegends.com/board/showthread.php?t=109533), you'll see Cho'gath listed as "hard to place on a team". I agree with this assessment!
Cho'gath is a difficult champion to place properly on a team for a lot of reasons. The argument for not using Cho'gath goes something like this: Cho'gath is such an all-around mediocre champion that anything he does, another champion can do just as well or better. For example, Cho'gath as a mage would be outdone by Annie, Veigar, Anivia, etc. while Cho'gath as a tank is outdone by Shen, Taric, Rammus, etc. I totally understand this logic, and I'd agree that most people playing Cho'gath will fit into this general group. However, many times that a champion that otherwise would be bad, when played by the right person can be amazing. Now, I don't claim to be an amazing Cho'gath per se, but I do feel like when I play him it's much more viable than argued.
I prefer to play my cho'gath as a tank, and while I can / have been main tank for groups, often times it serves the team better for me to be an off-tank. Basically I spend my time mid/end game using my rupture to disrupt the enemies movements, silence important DPS on the opposing team, and stomp around making clicking on my teammates a pain. This can allow both the main tank and the rest of the team to move into the team fight safely. Cho'gath's range with rupture makes him good for initiating! I know a lot of good players will argue "rupture is so slow, you can easily sidestep it!", and again I -totally- get why people say this. It's true, that if you put a rupture right under someone's feet, they can just easily walk right off with boots. However! in a grouping of 3-4 people, it's very easy to put the rupture in a position that the other team is forced to take the rupture. for example, put the rupture a bit behind them, they either have to take the hit or move forward. If they move forward, that's when you move in and feral scream, now whoever is at the front is a fairly easy target for your team to pounce on, or at least harass. If they take the rupture, depending on who was hit, you can either move in and take advantage of their slowed speed, or if it was an unfavorable target, you can just ignore it and wait for renewed cooldown. Rupture's distance puts you at an advantage the same way Heimerdinger's concussion grenade gives you an advantage at mid-lane (mainly, you can harass and damage the turret from afar, whittling down the opposition and goading them into attacking you, at least previous to the nerf for that skill).
Admittedly it might not sound all that great, but actually it's pretty effective. I intend to include video footage eventually, though I don't know when I'll get around to it.
Summary: Cho'gath, best champion ever? not by a long shot! viable? depends on you, heavily. If you're willing to get good with his rupture timing, you can play Cho'gath successfully, hopefully the rest of this guide will show you how!
Why this mastery build?
9 points into offensive just for the CD reduction and 15% magic penetration, this helps supplement your rather average damage as a tank Cho'gath.
In the defensive tree, it's important to grab the dodge speed buff if you're getting dodge runes, and even otherwise. Some people argue that Ardor is a dumb defensive mastery, that no tank needs it, but this is definitely an exception! Cho'gath's early tankyness counts on him being able to get minion kills, attack speed combined with vorpal spikes is effective. The other defensive points are pretty standard.
Why these runes?
Marks (Reds) - Insight (Magic Pen.)
The alternatives are fairly bleak, you could get flat health/health per level, but it's really not worth it. I've actually tried Cho'gath with critical chance runes with some success, his physical damage is high enough to warrant it early on, a rupture + feral scream + critical hit at low levels can leave a lot of champions in a dire situation, also it helps a little with minion farming. Honestly, it's really not worth it, and I'm sure you'd agree.
Seals (Yellows) - Evasion (Dodge Chance)
You could take mana regen per level or health runes instead, I prefer dodge because often times I don't want to buy ninja tabi boots (because it'd be better to get merc treads or swiftness) and this helps negate the need for that.
Glyphs(Blues) - Focus (CD reduc.)
Rupture harassment is key to early game Cho'gath, and being able to use his rupture/feral as much as possible during the mid/end game is also very important. Cooldown reduction here is a must.
Quintessences(My Precious) - Focus (CD reduc.)
Same as above, it might be tempting to stack flat health on cho'gath to make him even more ridiculously difficult to kill early game, but it's really just not worth it. Sure, you'll be harder to kill, but you really don't need it if you're staying up on your minion kills.
Why these summoner spells?
Clarity - Clarity is pretty important, because rupture and feral scream are really mana hogs, and Cho'gath's mana pool is very lackluster. It also makes you a much better harasser early on! If you can land 80%~90% of your ruptures, your lane opponents will likely be forced back.
Flash - Flash is a must on Cho'gath! Often times when you hit lv 6, your opponents will grow VERY weary of approaching you, especially if you have been playing well so far, and even more so once their HP drops to around 400. If you land a rupture here, you may have time to move in for the kill, but often times it won't be that easy. With flash, you can close that gap after a rupture and instantly feast on them before they can even react! Also, there are times where you'll be rupture harassing a low champion at their turret, and you have your feast up, but you can't risk feasting and running out. Here, you can use flash to evade the turret immediately after your feast. Of course, flash is also great for escaping through walls,etc. like on most champions, but flash with feast is a deadly combo. In mid/end game scenarios, often the carry DPS champion on the oppposing team will be standing back or run off when they start getting focused, with a good flash feast, you can finish them before they can be healed up or get away.
Ghost - You could use ghost instead of flash, but I really wouldn't recommend it, the instant blink of flash is far superior. I used to use ghost a lot, but then I switched over to flash and I haven't gone back since. You could replace clarity for ghost, but again, it's just not worth it.
Teleport - it's useful same as for everyone else, but compared to clarity/flash, it's just not worth it for Cho'gath.
Why this skill sequence?
Rupture at lv 1 is pretty powerful, not to mention it knocks up + slows and has great range, if you use it properly it might land you a lv 1 kill. After that, you want to max rupture first, it's really your most critical spell, especially since feral scream recently got nerfed. It is important to get feral scream and vorpal spikes to at least lv 1 early on, feral scream is essential for helping a lane fight start out in your favor, and vorpal spikes will greatly help you keep up your minion farming, fueling your passive. Some Cho'gath players prefer to get vorpal spikes up fast, to maximize their farming and so they are very difficult to kill, however this makes you virtually useless in a team fight by the time mid game rolls around. Rupture damage and knock up combined with a couple seconds of silence can make an easy gank for your team. I've also seen some people who max our feral scream first, using it as a defensive maneuver to counter champions from killing their lane partner, meanwhile using vorpal to farm minions. This might be a bit more viable, but you're gimping your potential in my opinion.
Why these items?
Meki pendant - Cho'gath has mana issues, even if you're fairly conservative, it's important to have mana regen early on so he can stay effective in the lane longer. Some players circumvent this issue by leveling vorpal spikes first, which is an alternative, but gimps your mid-game abilities. If you make good use of your ruptures, keep up your last hits, and play smart in general, getting a meki pendant and leveling rupture first works out way better. Also many Cho'gath players aim for a warmog asap, so buy either a health gem or health regen pendant. This is understandable, but as I'll explain further in, cho'gath isn't about being a tank 100% of the game, he sort of has phases. This might sound odd or stupid, but just bare with me till I explain it later in the guide.
Boots of Speed - mobility by this point in the game is pretty important, it will help you close distance after ruptures to land your feast, land last hits on minions, etc. it's pretty important to be a mobile Cho'gath, more on this later.
Again, it might be -very- tempting to start building your warmog now, however instead:
Boots of Swiftness or Mercury Treads - Your mobility will be very important during the time you'll be getting these boots, it will make you much better as an aggressive Cho'gath, which is what you want around this time (early/mid game transitional period).
Warmog's Armor - Finally, the pinnacle of Cho'gath items that you've been waiting for. I'd suggest buying the belt first if you're doing well, otherwise try to grab the pendant and ruby first, in that order. Warmog's is key to tanky Cho'gath, it will make you fantastically better, there's no point skipping this item.
From here on out, it's mostly dependent on the game. If the other team's AP DPS is really putting you in a bad place, consider Force of Nature or Banshee's veil. Alternatively, if their AD DPS is pressuring you, consider Frozen Heart or Randuin's Omen. If it isn't obvious, when you've reached 5~6 items, it's fine to sell your meki pendant, or change it into something else. If you're having mana issues (shouldn't be), consider chalice.
Guardian Angel - Guardian Angel was recently nerfed, it only returns 750 health and 375 mana when you are brought back. Cho'gath is very much an HP tank, his appeal isn't so much in his high armor or magic resist, but instead in his extreme health and size. 40% of Cho'gath's usual 4k HP would have returned him with roughly 1.6k HP before the nerf, needless to say Guardian Angel's usefulness is much more debatable now. It's still got some decent buffs on it, but I'd opt for a frozen heart instead.
So, how do I play Cho'gath?
How to land rupture - Landing your rupture on champions consistently is a sign of a good Cho'gath player, it is key to playing him aggressively. Placing the center of rupture directly on top of a slow champion without boots will likely land you a hit early on, but that won't last long so here's some useful tactics for landing your rupture. Alone any one of these tactics will eventually become predictable, so you need to understand and use them all appropriately. Again, a lot of people argue that rupture is unreasonably easy to dodge, but with practice you can learn to make it -very- difficult.
Against melee champions: Often times melee champions are very predictable, especially during laning phase. When a minion is low on your wave, and it's fairly certain that the melee champion will try to grab the last hit, preemptively set your rupture on the minion with the center off towards the direction the champion will be coming in from.Then as they are about step into your rupture's outer circle, set your rupture, the best case scenario is you hit them and stop them from getting the last hit, likely worst case scenario they get somehow manage to move out of it in time, but lose the minion kill chance. Similarly, it can be fairly obvious when a melee champion is about to attack you or a friendly champion, and you can use your rupture to protect them in this way, place it on your friendly and wait for the opportune moment to knock the enemy up.
Against ranged champions: This is a bit more difficult than melee champions but you might be surprised that it's not as difficult as it seems. Early on ranged champions need to stop significantly long to shoot minions and last hit. If you stay close enough to drop ruptures on them during these intervals, you can time your ruptures on top of them before they stop to shoot. This requires that you get a feel for how they're farming last hits, and for you to watch your minion pack's HP. Often times ranged will stay out of reach till the last second when the minion is low, then they'll step in and kill it, only to back off again. During their step into range, that's the sweet spot for timing a rupture. Another trick is if they are attacking you, place a rupture directly in front of them then step back away from them, they will often walk right into the rupture due to their ranged auto attack.
Against groups/teams: because people tend to bunch up for defensive/offensive as a team, they are perfect targets for a rupture. I advise placing a rupture behind them when you're trying to get them to advance, this will force them to either step back into it or step forward out of it. If they step forward, be ready to move forward and feral scream them, this gives your team a chance to jump onto whoever stepped forward. If the person isn't someone you want to jump on (Rammus at almost full HP inside his own turret range), just back off, no harm done since they're silenced and can't pull you back. Of course you have to watch out for things like Anivia's stun from afar while you step in, but that's out of scope of playing Cho'gath and should be general gameplay knowledge. When the other team is pushing you back and you need to buy time, simply place the rupture ahead of the enemy team, either they'll have to stop to let it go or take it. Try to place your ruptures in a way that they just barely would hit someone if everyone stopped moving, but still far enough out that they would get hit if they keep going in the direction you expect them to go.
Brush rupturing: This is fairly small tip but it's useful to keep in mind. Players tend to stay either as close as possible to you in the brush or as far as possible while still being in range for XP from minion kills. If you can determine which is more likely, you have a good chance at placing your rupture on them. Because it's in the brush, players often don't notice the rupture effect on the ground and don't step out of it in time.
General tips: It's important to note your terrain, for example if you're in a narrow corridor, such as the lane between top outer turret and top middle turret, players will be more likely to step backwards or forwards to dodge ruptures, whereas in wide areas like mid they're more likely to sidestep. Keeping these patterns in mind, along with how the other player is generally moving can often allow you to place ruptures in a way that will mystify your opponents a little ("how did he know I'd run into that one?"). This is probably the most difficult way to land ruptures, but it's also important to note and utilize, practice makes perfect. Sometimes people stand behind their melee minions and in front of their ranged minions during laning, this basically sandwiches them and makes for a -great- rupture target since you can hit minions along with them. Also, keep your eye open for when two champions are sticking very close together, they often bumble and bump into each other when you place a rupture on top of them both. Lastly, when you've pushed them to their turrets in a lane, you can frustrate and drain their chances at gold by putting ruptures in front of your minions, allowing the turret to grab kills while they have to wait for your rupture to pass.*edit*: I forgot to mention one of my favorite techniques for landing rupture. Often times, immediately after your lane opponents finish your minion wave, they move along with the minion pack forward along the path. If you place a rupture ahead of them on the path slightly right as you're turning around to move back, often times you'll surprise them and land a rupture that they just habitually stepped into. It sounds like this sort of trick would only work once or twice, but it seems like it's a pretty hard habit to break because in my experience people still step into after the 3rd/4th time. This is probably because by the time it happens again, they've already forgotten to avoid it, and even when they realize it, they realize too late and still get caught in it. There are, of course, people who remember perfectly well and will not fall for this trick often, but it's still worth a shot once in a while, especially in the heat of a battle when you're being chased down.
Note: this build is compatible with solo laning but these following guidelines may not be.
Early game (levels 1-6~8) - If you are partnered with a strong DPS champion, rush to the brush and wait with a rupture centered on the very edge of the brush where the opposing champions will likely step in. If you're partnered with a good CC champion, for example Sion, Taric, Pantheon, etc., let them hit first with their CC, then place rupture so that you don't waste a knock up and slow duration on a stunned target. If either your partner is too slow in getting to the lane, is a support, has no useful CC, or your opposing lane champions are just too annoying to risk it (Blitzcrank/Taric might be a good example), then just stay by your turret and wait for minion waves. During early game your mana regen and mana pool are pretty meh, it's important that you conserve your mana for ruptures you're certain will hit. It might feel a bit nerve wracking to wait, but trust me the opportunities will roll in and you only need to hit a few ruptures to put the other team in a bad place. If you're really struggling to land your ruptures, focus on pushing the other team back to their turret, this will put you in a nice place, it's pretty easy to land ruptures on people near the turret (less room for them to move around and no brush). Also this gives you a chance to stand around and regen mana. If you get low on HP, it's ok to use rupture on minions to give you some easy 1-2 shot kills with vorpal spikes. In fact, I would prioritize keeping your HP up to harassing the opponent with rupture, but if you play well you shouldn't be losing much hp due to your range harassment and passive healing.
If you get forced back to your turret, just use rupture to farm from safety till you have enough HP to risk hitting minions with your basic attack. Make sure you have enough mana for 1 reserve rupture though, in case they try to dive you, place it on yourself and stand behind your turret so that even if they kill you, very likely they will go with you.
When you get your feast at lv 6, unless there's a -VERY- good chance of you getting a feast kill on a champion, start feasting minions as much as possible! When I started playing Cho'gath originally I made the mistake of holding out on feasting minions with hopes of saving it for a champion, but it's NOT worth it. I can't stress this enough, you will see the benefits of getting to 6 stacks before you start aiming for champion feasts. Also, with reduced CD, the wait isn't horrible, most of the time you'll have feast when it counts. Try to feast the siege minions (guys in the tanks) so you can get the most gold out of your auto-kill, be aware by veryyy late game they won't be 1-shot kills, feast always hits for 1000 damage to minions exactly. This is also important to keep in mind when killing golem for buff, keep enough mana for feast when he's getting to around 1000 HP, careful not to feast before that or else you'll waste it.
Mid game (levels 8~14) - By now you should have your swiftness boots or merc treads, have around 3-4 stacks of feast, and hopefully enough lane control to allow you to leave your lane to help gank mid. Ganking with Cho'gath involves coordinating with your mid teammate. Let the other team's mid player push up, run in and rupture behind them, as almost all mid players will run backward directly to their turret when they think a gank is imminent. Silence them, start wearing them down with vorpal basic attacks, and finally once they get low enough, feast them.
You don't have to gank, of course, and sometimes it's better not to try because it's too risky. However, it is very important during mid-game that you assist your team in any skirmishes, pushes, or anything else where you'll need most of the team (fairly standard stuff). Use rupture to initiate, if your team backs you up and you get into a skirmish/team fight, you'll want to feral scream their highest DPS champions best you can. Try to stand in the way of melee champions, or atop your friendly champions to block target spells. Your job as the tank is essentially to be as annoying as possible, do everything you can do disrupt their plans, rupture interrupt channeling spells, silence casters, feast their tank when he's getting low (yes, sometimes it's better to feast the tank because your damage burst from feast is massive and can punish an overzealous tank),etc.
End game (levels 15~18) - From here on out, you should be keeping your feast stacks at 6 and rarely dieing, yet you should almost always be the first person in on EVERY team fight. You'll be the one taking turret fire, the one who goads the team into blowing all their stuns and CC. At this point you should have a gross amount of HP, MR, armor, along with slowing effects from randuin's omen and frozen heart, along with banshee's veil, etc. Basically it should be a pain and then some to take you down. Normally this means people wouldn't focus you, they'd try to ignore you, that's where good ruptures, feral screams, standing on top of your friendlies, and blatantly charging in ahead of your team ("oh this cho'gath is ******ed, burn him down before his teammates get in!", except then you survive and all their skills are on cooldowns, sure you're pretty damn low but just know when to turn around and let your team take over while you get out of focus. flash is useful here too!) can make you the primary focus.
Hopefully you get picture. I'll try to put up more detailed information if it's requested or any specific questions are asked. I might do some video guides or screenshots of examples for how to place ruptures. Till then please:
Please comment! Critique! I don't mind if you think this is the stupidest build you've ever seen, just tell me WHY and be specific! Thanks for reading!