Hi My name is Snowyz ,playing since S2 end - S3 .Im a unranked player who climb up to silver 2 in S4 ( i just did my 10 ranked games and i stopped cause it's wasn't fun :/ )
Today i will show you how to get fed as godzilla and carry late game with kog'maw

First of all , Kog'maw isn't a great laner , he can do things ( less than lucian or miss fortune ) but can't really trade .
he is weak against Champion can go in , CCing , tank , lock down , burst , like every adc you may say , but kog'maw is one of the slowest champion (325) whitout any escape or "CC" , cause his E isn't a real CC ( every other champion with 325 MS got a buff MS or a dash / escape / CC )
Master Kog'maw is master his lane facing . if you are not behind , and you get your RageBlade/berzerks before the IE/ER enemy ADC , you must fight and win trades

Pros:
-Hard Late game Carry
-Massive damage Hybrid ( %HP , Magical , Physical )
-Long Range with his W ( 710 , more than Jinx with rocket launcher )
-AOE Slow ( E )
-Armor shredding ( 28 % armor and MR )
-Finisher ( R )
-Versatile Build ( can build everything that deal On hit damages )

Cons:
-Low mobility
-No escape
-Need hard defensive support ( or 2 , one mid and 1 bot )
-Mana Issue if Spamming
-Early game not that good

Stater #1 :+
- Typical starter for ADC , strong ,good laning + LS


Stater #2 : +
- When you got possibilities to get this item , get it . Kog'maw is a Hypercarry Late game , so 450 Gold helps him a lot. but it's a high risk , medium reward item , cause you will get difficulties in lane , low survival abilities , no HP pool (thanks to Doran Blade)

-A Really Good One , buy it first , it's not a joke . Kog'maw synergy with On-hit effects is godly and he Scale with AP and AD AND AS ! This Item Give the Best Amount of AS (64%) in the entire game ( the only thing that give more AS than this is Jax Passive Relentless assault , up to 88 % AS boost late game with 8 stacks )


-This is a On-hit item that deals 6% of current enemy Health , give AS and some AD + Active deal 10% max enemy HP and a MS boost , perfect item for our Caterpillar


-One of the best enemy of ADC champions are Assassins and APC are often roaming botlane to get fed. if that scenario is finished and the APc is not fed , get this !
it give 40%AS , 40 MR and 40 on-hit Effect , and like i said , our Caterpillar/Godzilla is good with on-hit effects

Good one :+ +
-Since Kog'maw deals hybrid Damages , Rageblade scale AP , and Gunblade heal 15 % of any damages deal , it's really Good !

-Runaan Help him a lot , Rageblade + Runaan = machine gun
(Runaan deals 15 on hit damages can help)

-I see a lot of kog'maw build BT , it's not a bad choice but lifesteal synergy with kog isn't the best . however , the shield is nice and give a lot of AD

Bad one :
-Kog'maw deals hybrid Damages , Death dance isn't really reliable on him , maybe death dance passive will prevent from burst but not strong enough


-Trinity Force , it was a godlike item on him , but now , he can't cast spell between AA so Sheen can't Procs + critical Strike is meh ...


-Infinity Edge is not really good on him cause of his W , allow him to go through AS cap but reduce 40 % of his Damages output ( on hit effect doesn't count)
So Critical Strike are not viable and IE isn't worth enough to make Critical viable



Boots of choice :

-Berzerks are godly on him , scale very well (60% with W)


-mercury are good agaisnt CC , and APC (if they are fed , there is no way your boots will help you)


-Swiftness are Op right now , give 65 Ms and kog'maw lack of escape , so it's a good idea to pick them ( only for 900 Gold )


-Never tried but sounds cool since Kog'maw Deal magical damages too

Enchant on boots : or

Against "people who don't really like you":



+

-Need something useful against assassin ? Get your GA! it's sounds business but it's the truth , GA help a lot and it's a late game item so you can skip 1 item for this



-Mercurial is for the hard CC , or Zed ( cause Zed don't give a f*ck )

Kog'maw works well with Support who can protect him (, , )

Offensive Champions are not that bad but Kog'maw's late game need protection , and can pell but not harder than a good or
+/ works well with kog'maw W