This build allows you to harass early on in the game, and with the 26/0/4 masteries, you deal tons of extra damage to both minions and champions, helping your early game tremendously. The purpose of this build is to allow the neutralization of enemy tanks and close ranged carries. By the end of the game, you should be able to focus a single tank and melt him/her within several seconds. If any squishy gets in your way, they die in only a few hits. However, if you get focused, your Guardian Angel will ensure you live long enough to kill them too, or allow your allies to kill them.

The build is really simple, just rush Berzerker's Greaves and Malady. Then go for the Gunblade before Madreds. Take the Bilgewater Cutlass first for the lifesteal, and the Hextech Revolver before getting the full Gunblade.

The Madred's Bloodrazors are after that. Start with the Recurve Bow, then work into either the Pick-Axe or the Madred's Razors depending on which you immediately need.

After Madreds you go for the more heavy hitting Black Cleaver. Once you have that, the damage from your W will be significantly increased.

Lastly, get Guardian Angel, because if you get focused early on, you can come back and finish off anyone who hasn't immediately found out you're still alive.

During the laning phase, try to partner up with someone who has a knock-up, stun, snare or fear. Note that if they only have a slow, you need to stay behind them, as that won’t do much in comparison to other types of crowd control. Personally, I like to lane with Cho'Gath, Fiddlesticks, and Leona. Cho'Gath's Rupture (and its subsequent slow) are extremely helpful in grabbing kills, considering your Bio-Arcane Barrage's range and extra damage. If you're level 6 and have your first level in Living Artillery, it becomes extremely easy to get off two or three ults off on the poor victim's face.

For Leona, her passive is extremely useful for putting even more early-game damage on your enemies, and also useful for grabbing kills with your ult (it procs her passive for extra damage).

During the pre-minion spawn time period, be sure to stay behind your partner and let them enter the bushes first. If there are enemies inside, don't be afraid to fire of a Caustic Spittle at the one taking damage and shoot them. Always lead with Caustic Spittle as it lowers their armor and magic resistances, making it easy for both you and your ally to damage them. If you are communicating through third-party VOIP programs, it becomes considerably easier to focus on one of them. If you die first however, be sure to make full use of your passive, as it can grab a kill, or allow your partner to the same.

When the minions arrive, thanks to your masteries, you can easily last-hit minions, though I personally attack them myself (and then last-hit them) rather than let minions take their time to damage them. This allows you to push the lane early and with Bio-Arcane Barrage, you can hit the enemy/tower from a safe distance for an extended period of time. Even if they attack you, you should be out of tower range. Don't be afraid to poke them from within the tower's range; as soon as the firing animation has completed, back up to avoid the tower blast.

Once you have your ult, sniping/poking enemies hiding by their tower is extremely easy. Even if you don't kill them, they're tower is open to attack. Take advantage of this. If you have pushed your minions as much as possible, you will be able to quickly take out their tower before the ten minute mark.

Once the tower is down, be sure to push the minions a bit further before roaming. By now you should have your Berzerker Greaves and Malady (along with your single Doran's Blade). This will be enough to kill most enemies within several hits. If you've had a good early-game you may also have your Bilgewater Cutlass and maybe even your Hextech Gunblade if you've done very good. Be sure to keep an eye on your own lane after you've left it, just in case they try and push it while you're gone. With two people free to gank, their team has to be sure to play defensively, making them excellent targets for your ultimate as they hug their towers. If they've wandered out too far, there are several processes by which you can kill them.

If you have allies in that lane, then hit the enemy first with your ultimate at a decent range. Let them know you're there. Usually, they will run, knowing they need to back up. If you're team has good communication, your ally will immediately attack them. By that time the enemy will be within range of your Bio-Arcane Barrage. A few shots of that and maybe an ult or two and they will be respawning in twenty.

With your Caustic Spittle, Bio-Arcane Barrage, Living Artillery and Cutlass/Gunbade's active, you can nuke just about anyone to half heath, and thanks to the item's slow and long range, you will be able to hit them for a long time, getting them down low enough to finish them off with Living Artillery, if it’s even needed by that time.

Don't be afraid to spam your abilities, such as your Caustic Spittle. Their mana cost is very small, and don't increase with ability level. Your innate mana-regen will easily allow you to stay in lane for a while before you have to leave. Odds are you'll die before you run out of mana.

The specific runes allow for a 1.0+ attack speed with only Berzerker Greaves. By then end of the build, you will have 2.2+ attack speed. In the early game the runes allow for fast and efficient poking, as well as, well, getting more hits on them. The Attack Speed runes sync well with the 10% Crit Chance runes; the more you attack, the more chance you hae to critically hit. I can't tell you how often those lucky crits have saved my life or killed them with a bar of health left.

A few crits early game lets them know they need to be careful and they will begin playing more carefully. It essentially plays mind games with them, and for Kog'Maw, a defensive enemy is a dead enemy; As soon as they start backing off, they lose last hits, they lack poking ability, and they don't venture too far beyond their tower, enabaling you to hit it from a safe distance with your speedy BAB.

Late-game, those crits kill squishies, as they tend to proc often with your fast attack speed. However, they don't do much to tanks late-game. Thats what the Black Cleaver's for.

Once you reach level 8, you should be able to get the Blessing of the Lizard Elder Buff. However, you will likely have to blue-pill for health. By the time you're level 11 you should have your Bilgewater Cutlass at least. With it, you can take the buff with no loss of life at all. Be sure to grab this as often as possible, especially if you don't have jungler. If you do have a jungler, be sure not to mess up his course. The last thing you need is a jungler who won’t gank for you because you messed him up, in which case the buff will likely got to waste.

The Crest of the Ancient Golem can be useful, but only if you have a tendency to spam your ultimate. Otherwise, it's mana regen bonus is lost on Kog'Maw's already low mana ability costs. For this build, it shouldn't be needed, but if you're in the neighborhood, don't forget to donate it to your nearest AP carry.

Champions who have Attack Speed increase buffs, such as Nidalee, Warwick, and Nunu, can be of great help to you. Be sure to ask for their buffs when attacking towers with them, depending on their level, you're Attack Speed can go from 1.1 to 1.7. In a fight, this can mean the difference between life and death, a kill and nothing. Its very nice for hitting turrets.

Baron buff can be useful only for its increase in attack damage. You'll likely be so squishy the buff's healing effects won't affect you much (or have time to kick in if you get focused). Thankfully, Guardian Angel will help you out a little bit, if you manage to survive the fight.

Often times, I see Kog'Maws who don't take both Flash and Ghost, and usually they die. Both spells are essential to a Kog'Maw's survival, especially with this build. Flash allows you to place to initial distance between yourself and an approching enemy, or to juke like any other character. Ghost is more of a utility spell used to chase or run from distant enemies who you know will catch up to you if you don't use it.

Mostly, I use Ghost to chase people down. Since Kog'Maw has one of the slowest move-speeds in the game, its required to have in the event of a fight. Somtimes an enemy will get too cocky and chase you even though you're behind your friends. He'll plow through them jsut to get to you. At that point use either Ghost or Flash to evade them, and then when they realize they won't catch you, they'll turn around and re-enter the fight.

That is the point where you turn around and hitt hem with everything you've got. In that sitation, I would op Ghost so I can run away, but also run back in case they turn around, allowing optimal time to wail on them.

Pros:
1. Super easy to get kills (+KSs)
2. A friendly support's best friend
3. Can whittle down enemy tanks from long range.
4. Can cause Post-Traumatic Shock if you use the Dragon Dance Kog'Maw skin
5. Places butterflies at the top of the "Most Dangerous Insect" list (Butterfly Kog'Maw skin required)
6. You will never think of reindeer the same way again. You won't be getting coal this Christmas...
7. Innate ability to cause targets to flee in terror
8. Require the enemy to designate several players to go after you, leaving them open to counter attacks from your allies. Your passive makes for a great initiator; you might even get a kill or two!

Cons:
1. Besides GA, you're extremely squishy
2. You need at least a decent early-game to get your core items
3. Once you're caught in a CC, you're likely dead (snares have a 75% chance of survival depending on the situation)
4. You need to be guarded to ensure you stay safe through the fight
5. Most won't want to do so
6. One enemy carry missing can be the death of you if they surprise you. As long as you know they're there and are prepared, you'll do fine.

That's about it really. Just watch those blind spots and bushes if you're alone and you'll do fine.