Not Updated For Current Season
Simple build I made for Kog'maw. Great for ranked games.
Doran's Blade (X2) : Best starter items in the game, but sadly they cannot be build into anything. You can get 1 if you're doing very well in lane,but if not, you can grab 2 for extra health,damage, and lifesteal.
Berserker's Greaves : Nice attack speed for start, later you can sell for Mercury's Threads.
Madred's Bloodthirster : Attack speed,damage, armor(a little bit), and the PASSIVE! On hit, 8% of the target's health dealt magic damage. Rapes with his W. With the target's armor/magic resist, Kog'maw can do around 10% of the target's health with his W.
Infinity Edge : His only crit item. Rapes : nuff said
Frozen Mallet : You need this to non-squish yourself. The passive works very well for Kog'maw's great range which helps you chase and catch up.
Bloodthirster : His only lifesteal item. Farm lots and get tons of damage.
Last whisper : Awesome 40% armor pen. Everyone has armor, this item does not have to be only against tanks.
Pots : You eat pots if you go to a late late late game. I've had an 80 minute game once.
Best late late late late late late late late game items : 2X Phantom Dancers(replaces boots), Infinity Edge, Black Cleaver, Bloodthirster, Last whisper. (You can swap one for Madreds if you want, but I find them all necessary)
Pretty standard DPS runes
Not much seal choices for Kog'maw. He doesn't need dodge and etc. And secondary runes aren't that great so I get mana regain for his ult spam in some cases.
If you want, instead of 21/0/9, you can go 9/0/21 for the movement speed buff,mana regain,creep buff durations cd, etc.
Cleanse + Ghost is what I would recommend.
Cleanse : Removes debuffs(now removes Exhaust)
If you get targeted and get blinded,stun, etc, you'll be useless. This would help out a lot.
Ghost : Great for escaping and chasing, especially when you have a Frozen Mallet.
Flash : Would be great to do a last hit or run away.
Ignite : Can be used to finish someone, but I rarely use it for a high damage dealer like Kog'maw who can finish someone off easily.
Exhaust : If you're doing ranked games and you see a lot of DPS characters that would tear you apart, this would be a nice choice.
Spells you shouldn't get :
Heal : Meh, you have better choices.
Teleport : Not really much of a need.
Smite : He's not a jungler.
Clarity : This is a DPS build, not an AP build. Clarity is used for mages who run out of mana.
Clairvoyance : His ult can be used to show bushes already.
Rally : Rofl-nuff said
Fortify : Only taunters or junglers should use this spell.
Revive : It's ok after the speed thing buff, but you don't really need it.
Please post comments and rate my build. Thanks. =D