Kog'Maw is a deadly carry with Bio-Arcane Barrage letting you auto attack from so far away PLUS deal damage as % health. I build him as an AD carry because at the moment that is how he best fits into the metagame. This build focuses on building AD, because with a lot of AD you can poke more efficiently with Living Artillery AND kill squishies in 3 or 4 hits. I no longer like building Madred's Bloodrazor because it is easily countered by magic resist, and you simply get more damage output by taking advantage of his innately high attackspeed and building AD.

I would like to thank Restrictnine, as he is the one that showed me this build. I have been playing Kog for a long time, but he opened my eyes to building this way. :)

- Upon dying, Kog'Maw starts a chain reaction in his body which causes him to detonate after 4 seconds (he can move in this time), dealing 100 + (25 x level) true damage to surrounding enemies. Kog'Maw will gain additional movement speed upon entering this state

Run at people when you die, you blow up and deal true damage (cannot be mitigated). I would like to point out to keep this in mind if you think you will probably die from a gank. You can turn around and get one of your gankers low enough to kill them with your passive. By no means TRY to die, but keep it it mind.

- (Passive) Increases attack speed (Active) Kog'Maw launches a corrosive projectile which deals magic damage and reduces the target's armor and magic resistance

When you use the active the passive does not go away, so there is no reason not to use it when you start DPS'ing someone. I usually wait to see if a level 1 fight breaks loose before I skill up, so I can take Void Ooze if I need it for a lvl 1 fight.

- (Active): For 6 seconds, Kog'Maw's attacks gain additional range and deal a percentage of the target's maximum health as magic damage (max 100 damage to monsters).

The wording here confused me when I first started playing Kog. From the wording it sounds like this effects his skills (caustic spittle, void ooze, living artillery) but in reality it only increases the range of his auto attacks. So do not use it to try to finish off people with your ult! :) This is the bread and butter of attackspeed Kog. This is what you should use every time you start dpsing in a fight, and to harass in lane.

- (Active): Kog'Maw launches a peculiar ooze which deals magic damage to all enemies it passes through and leaves a trail for 4 seconds which slows enemies who stand on it.

Nothing much to explain here. I will go over positioning of this later.

- Kog'Maw fires a living artillery shell at a great distance dealing damage and revealing targets for 4 seconds. (150% bonus damage to champions).

* Cost: 40 Mana (each subsequent Living Artillery in the next 6 seconds costs 40 additional mana, capping at 200 per cast)

* Area of Effect:

I just wanted to note the extra mana cost for Living Artillery's used in quick succession, and that it has a small area of effect (aoe). I will go over positioning of this skill later, it is very vital to success. After a recent patch this now scales with BOTH ap and ad, which with this build makes it great. We don't rely on this for the majority of our damage, but with this build it can do significant damage to fleeing enemies.

Starting Item(s)

(recommended)

(going against a heavy AD harasser)

(going with a healer bot, easier last hits)

I greatly prefer Boots route. It lets me dodge in and out to last hit, AND lets me harass my enemy with my W more effectively. The boots (and possibly movespeed quints) will give you a real advantage in speed, and in a sense helps you be more survivable. However, I understand that some people may be uncomfortable without true survivability on Kog, so I have included the Cloth Armor and Doran's Blade options. Build the cloth armor into Madred's Razors if you choose to go that route.

Laning

I honestly believe the best spot for Kog is being bot with a good babysitter (ex: Janna, Soraka, Sona) that will let you have all the creep kills. However if this is not an option (at low levels people don't usually support) you might have to take your chances in mid because Kog NEEDS early game farm.

Attackspeed Kog is very weak early game, but he needs farm. Look at the other team. Do they have strong mid heroes / mid heroes with gap closers? (ex: Caitlyn, Annie, Kassadin, Akali) Try to guess if these champs will go mid. If you think they're going to go mid or a Clairvoyance let's you see them mid, please, do not go mid, they will own you because all you have to counter them is Flash. However if a passive champion is going mid such as Ashe, Malzahar (just don't get close when he's 6), or Tristana you can go mid.

IMPORTANT! Keep in mind if you're going mid against a heavy harass ad champ ( Miss Fortune, Caitlyn, Vayne) to get a Cloth Armor and 5x Health Potion's for your starting items. If you're going against a tough mid AP you probably want to go Boots x3 Health Potions so you can avoid their skillshots and have sustain.

I don't usually bother harassing until level 4 or 5 because the creep aggro you get will often hurt you more than you hurt the enemy. If the enemy is being dumb and getting up in your face then by all means, hit them a few times with your W active. Once you hit 4 and they are within attack range throw out your E, your Q, then activate your W and hit them a few times, but don't chase them too much and get attacked by their minions. Keep in mind this combo is very mana intensive so don't waste all your mana doing this over and over.

Once you hit level 6 and get Living Artillery (R) it will become even easier for you to harass and get kills. I usually have trouble getting kills before level 6, but it still happens sometimes. When positioning your ult make sure to aim it a little behind, or to the side of the enemy (whichever way you think they'll run). I typically don't use E when I harass with R. I find it easy enough to hit the enemy roughly 50% of the time, and if you always wait 6 seconds between casts of your R you shouldn't run out of mana too fast.

Aiming Examples
Note how I try to get Ashe in the middle of my E so that as she runs she'll remain slowed for longer.
See how I am it just a little behind Ashe? Her natural instinct when she sees my ult coming will be to run backwards, right into where I actually aimed it! If you notice they aren't paying attention and REALLY bad at dodging, don't do this.

First return

Your priority will be to buy Wriggle's Lantern ASAP. Try to get this on your first return. You can then use your wriggles to ward to see the jungler coming, or ward your brush (bot lane) for easier killing/harassing.

Here is a guide to effective warding if you are curious where to put them!

http://www.leagueoflegends.com/board/showthread.php?t=237514

You should only gank if you went mid and the other mid is dead or b. If you are bot just focus on farming / getting kills in lane / controlling Dragon.

If you have the opportunity to gank, Kog is a formidable ganker. However, you do not always get this chance if you're playing against a strong mid champion that you cannot manage to kill. If you do kill your mid counterpart and have at least half health, you can go ganking!

Head up to top or bottom lane (whichever one is either giving your team more trouble or the enemy has pushed up too far) and sit in the brush by the river. If you know there is a ward be prepared to run in (hopefully with ghost) and try to surprise them as best you can. Make sure your team is ready, ping the target you want to focus, and go in!

Throw down your E in such a way to ensure they run into it while they're fleeing and get slowed. Start pounding them with your Q + W. Once they are out of your slow and still might get away use your exhaust if you can. If they run into the brush to avoid you throw a R in their direction to get sight on them and keep hitting them with your W. Still not dead? Finish them as their running away with your R. Keep in mind during this time your teammates should be helping you kill them as well, so this should be easy as cake if you do it right. See the pictures below for positioning references.
I have just popped out of the brush and the enemy was past the river. So I use my E in a way to ensure they will run into it and be slowed.
Here I'm chasing Ashe and trying to finish her off with my R. When you're doing this ensure you lead the target with your ult so that you calculate the delay with where she will be at the time in lands. You will have to change this based on their speed, you will just have to guess and get used to it.

Work on farming up your Infinity Edge. You should have it by the end of mid game so you can transition into late game as a force to be reckoned with.

Be sure to participate in team fights if they need you. There's no point in farming if you're letting the other team get fed because you aren't helping with team fights / defending towers. This phase is all about map awareness and knowing where to be and when.

Kog needs red buff. Try to get Red Buff if you can. This will be a great asset in ganking and team fights in general. You are the AD carry so this should always be given to you unless you're doing poorly.

Blue buff isn't very good for you. You don't use too much mana and your cd's are relatively low, but hey if no one else wants it I guess you can take it and spam away with your R!

You are the carry. You are the one that picks out the highest priority target and murders them. However, you are also very squishy yourself. When positioning for a team fight make sure to stay behind your tank and melee. Even when you're running around try not to bunch up or stand on top of your tank. Stay safely behind the front line, probably along with your support / casters.

If the teams are duking it out seeing which one should initiate first, poke a little with your R. It won't do too much damage so don't spam it and blow all your mana, but even a little damage and sight on the enemy team is very beneficial, and you have the range to pull it off.

Once the fight is initiated throw a slow in the middle and pick out your first priority target. Usually this will be the enemy carry or mage (ex: Caitlyn, Vayne, Brand, Fiddlesticks). If they are not in range of you to safely dps them with your W, switch to the 2nd top priority kill. Maybe this is a support or offtank. Prioritize Melee carries over range carries because it will be much easier and safer for you to kill a melee. If an assassin or another carry comes and tries to kill you Exhaust them and teach them a lesson.

Make sure to finish off fleeing champions with your R if you can, but remember don't chase too far and leave your team still fighting without their carry. It is very vital for you to keep dishing out sustained heavy damage during the team fight.

Stay with your team. The key to winning late game is staying together and having good initiations on teamfights.

Late game is all about sticking together and fighting / pushing / defending as a team. Like I mentioned in the Team Fights section, when roaming around make sure to stick behind the tank. If you are farming, don't be far from your team, and don't be in lanes far away from turrets. If you get caught with your pants down it could mean gg for your team because it will be hard to win a team fight 4v5.

By now you should be able to melt almost anybody on the enemy team. Because of this the enemy team will be really keen on killing you first. This is why it's so important to get survivability items and stay behind your tanks / melee. If you are having trouble staying alive consider buying a guardian's angel on top of your Banshee's Veil.

Lots of times items are situational late game to counter specific heroes / teams. I will discuss situational items later.

So there are many uses of Kog'maw's Living Artillery. A lot of people overlook the great scouting opportunities your ult gives you. Here are some examples of how to use your ult like a pro!
You can snipe people turret hugging with low health. This is doable at every in-lane turret by hiding behind trees, or even just sniping them from the lane. If you are hiding in the forest be careful because their turret will still attack you if you are too close when you hit them.
Use it to check brush for possible ganks when enemies are MIA. Also check brushes that some teams like to sit and wait for you to walk by such as the brush by blue buff and baron.
Check to see if important neutral creeps are still up such as Dragon, Baron, Blue Buff, and Red Buff. Hopefully you should have wards to see if they're up but this is a good alternative if you don't have wards at all of these.
I've shown this earlier but I just wanted to reiterate the importance of leading your target when you're chasing with your ult. Keep in mind if they're ghosting / have a speed increase you will have to aim further ahead. This is roughly the distance you will need to aim ahead if they are just running with only regular boots as a speed increase.

Some clarification on item choices:

Simply the best boots for Kog. This will net you much more damage than Sorcerer's Shoes with the AD build. If it rolls into late game and you need survivability replace zerker greaves with Mercury's Treads.

I feel like this item makes up for Kog's relatively weak early game. The armor and lifesteal lets him be more aggressive in lane. Once Kog gets this item he can start properly participating in fights without losing trades.

I like getting this before IE since it's cheap and the movespeed will help you a lot in chasing / killing (with your W and R).

This item transitions you into being a true carry that deals massive damage. I like IE because it works well with your Phantom Dancer and crit masteries. Some people prefer Bloodthirster over IE but I will go over that in situational items.

Gives you much needed attackspeed and movespeed which work great on Kog. The crit chance will work nicely with your Infinity Edge.

Champions have built in armor gain through levels, and if the other team is smart they will be building armor (especially since the current meta promotes 3 AD champs on a team). Combined with the debuff from your Q this will make armor a non-issue.

This is a good survivability item for everyone, and I feel like it is quite helpful at this point in the game. This will make it cost a lot more for the other team to dive you, since if they kill you they have to wait for you to come back up and kill you again. In this time your team will be wailing in them since you should've been in the back of your team.

Before you go "WHY MORE THAN 6 CORE ITEMS?!" listen to me. I only list this as a core item because you should replace your Wriggle's Lantern with Bloodthirster if you max out your item slots. More lifesteal, more damage. You lose the nice proc for killing baron, but the increased damage should balance it out.

This is one of my favorite survivability items, but it is situational. I would get this if the other team has big suppresses / stuns that will kill you if you get caught. The reason this is better than Banshee's Veil in those situations is a BV's passive can easily get taken off, then you will get caught. However, with QSS you can choose when to take off CC, and as long as you have fast fingers it is better than BV.

This is a good survivability item against a mostly mage team, or if one mage on the enemy team is owning you. Also a must against LeBlanc. As explained in the QSS section don't count on BV for the passive, use it as a health / MR item.

This is in the situational items because many people prefer to get it instead of IE as your first big damage item. It is definitely a good first damage item, but I feel like the lifesteal is unnecessary since you have Wriggle's Lantern and stacking up the thing is a bit of a pain.

A good option if you need some survivability and your team is being stingy with red buff.

A lot of people like this item on Kog, but to be honest I've never been a big fan. I don't like breaking my auto-attacks to use a spell for the proc, and it's very difficult to farm up. Still, the movespeed / crit / as / slow works pretty well. I would suggest replacing PD with this if you want to try it.

A great item if you are in need of magic resist because the other team's mages are owning you. I would suggest getting this earlier rather than later.

If the team is very high in cc, especially if they have assassins that will come for you such as Kassadin these are a very good option. Oftentimes people will sell their Berserker's Greaves late game and replace them with these if they are having trouble being cc'd to death.

If you are getting owned by AD champs on the other team you might want to get these, but the more common use is replacing Berserker's Greaves lategame if cc is not a thread but AD champs are.

Get this if you are having trouble facing heavy life steal / health regen heroes such as Dr. Mundo Warwick Swain.

- Cleanse is a great summoner spell for Kog because of his lack of escape abilities. It's really helpful for surviving kill lanes such as Taric + Vayne or Leona + Tristana. It also will save your butt when you get initiated on when combined with Flash. I generally find this to be the most useful summoner on Kog. Even though most carries take Ignite Kog usually stays at range; too far away to ignite someone.

- Flash is really good for saving your butt since you have no mobility without summoner spells. It also lets you reposition yourself easily in teamfights. It is simply the strongest summoner spell right now, as it gives you protection early game from ganks, and lets you escape those assassins that come after you during teamfights. Keep in mind you can Flash over walls when you get pinned in a corner.

Since we go down the utility tree, keep in mind Ghost and Flash will be on relatively low cd's, don't be hesistant to use them if you're afraid you're going to die.

Optional Summoner Spells:

- I like this spell for both ganking and survivability, and if their assassin gets up in your face during a teamfight you can exhaust them. I've also had many situations where an enemy tries to kill you as you're fleeing. If it is a 1v1 you can often turn around and kill them with exhaust as long as you aren't TOO low.

- This is typically less strong than Cleanse, but if the enemy has almost no CC you could get this. The reason you take heal instead of your support is because it will heal you more than if your support had it, and you will usually be taking more damage than the support. Make sure to communicate with your support to make sure the support takes exhaust if you're taking heal. You can easily bait kills with this spell early game, you just have to make sure the enemy carry isn't doing the same thing!

Suggested:

greater mark of desolation - You are building AD, so you will want armor pen to do more damage. You don't really need magic pen for your W, it is more icing on the cake than the focus of your damage. Arpen marks are a nice mark that fits for most ad based champs, including offtanks.

Greater Seal of Armor - This is a good rune to take because you will be doing a lot of trading with the other ad carry bot. It is also good in every situation. Armor seals are good runes to have in general since they're good for tanks, ads, offtanks, etc.

Greater Glyph of Scaling Magic Resist - Kog won't benefit enough from cdr or ap runes for this build, so I choose survivability.

Greater Quintessence of Attack Damage - More AD. You will be more scary early and these will help you last hit. You can say "I don't need help last hitting" but really ever bit counts. Make it easier to last hit, make it easier to win.

Optional:

Greater Quintessence of Movement Speed - This will make you a real nuisance early game and help you harass with your W. I find that it helps me a lot when chasing / harassing. Also since you have survivability runes for your seals and glyphs it makes it more viable not to take health quints.

Greater Mark of Attack Speed - This is really the only other viable mark in my opinion. You aren't at the attackspeed cap and it will also help you early game. However, I find it less noticeable lategame.

Greater Seal of Attack Damage - These will let you last hit even better, and deal a lot of damage from level 1. However, I don't like taking these unless I have a good sustain support like Soraka or Alistar since kog will take a lot of abuse from the other ad. Since kog has no dodges or speed boosts like Graves or Ezreal it's harder to avoid being hit with him.

Greater Glyph of Attack Speed - Will boost your attackspeed, but make you squishier.

greater quintessence of desolation - Boosts your ad damage, but harder to last hit with than AD quints. These are still a good rune to have since they work on a lot of champs.

Greater Quintessence of Health - Especially if you're a new player or just new to Kog these can be very valuable. They will help you stay in lane early game and survive harass. I have tried both and since I am an experienced Kog'maw player I can live without the extra health, but he is rather squishy, and these runes are great for giving you that early game survivability boost.

Pretty standard masteries. You want the crit masteries because of your IE/PD combo, and I like Vampirism because you get an early wriggles. I like going down the defense tree as kog, since as I explained earlier he'll take quite a bit of abuse in lane during trades.

An alternate mastery setup would be to take the same 21 points in offense, and take 9 points in utility. Grabbing flash bonus, good hands, swiftness, and increased buff duration.

5/31/2011 - Switched around build order. Changed recommended boots to zerker greaves because of recent change to Q. Removed Build 2 because of recent change to Q. Updated a lot of sections to reflect these changes / new patch changes for Kog / general playstyle changes I have come to (mostly early game).

2/19/2011 - Switched seals from dodge to mp5 and added the summoner spells section. Added clarification about build 2 / copying in intro.

2/20/2011 - Changed Masteries to 1 point in perseverance and 2 points in Good Hands.

8/4/2011 - Changed Malady to Phantom Dancer in main build.

11/13/2011 - Completely reworked build in accordance to current Meta. Focused on AD damage rather than magic damage / magic pen.

11/17/2011 - Guide description rehaul to match new build / playstyle.

3/11/2012 - Changed summoners, masteries, runes, and switched out BV for GA

I hope that this guide helps both newbie Kog's and experienced Kog players alike. I find this build very successful in carrying in my experience, and I also think it's fun. Please don't say "oh I like AP kog better so this build is bad" or **** like that because that's not what this build is about, the playstyles are completely different.

Thanks a LOT to Lord Fragamacrunch for helping me with calculating attack speed, posing in pictures, and all that good stuff. YTB! :D

Thanks to Searz for in depth feedback and suggestions that have made my build better.

Thanks to Restrictnine for helping me reevaluate my build on a more competitive level.

Thanks to Luther3000 for laying down the final straw so I finally updated my guide.

I am looking to continually update this guide, have a nice day, and a GG!