My name is Owain and I am not very good at League of Legends. I am tactically and mechanically disabled. I am however pretty good at maths and I have a deep understanding of the game, even if my body rejects this knowledge during game. You don't have to listen to me, I haven't earned it.

Kog'Maw is rightly considered a hypercarry. Weak early game, super strong late game. You can negate a lot of the weak early game with the right runes/masteries and a playstyle that works WITH him, not against him (assuming it's a he?!?!?).

Semi-standard ADC Runes, with an emphasis on attack speed. With W active you get an extra 20.3% AS!

Nothing remarkable otherwise.

Avoid scaling items as Kog'Maw needs the help early on.

6 / 18/ 6

Controversial? Shouldn't and ADC take 18 in Ferocity?

No. Kog'Maw is not your traditional ADC and we're building to his strengths.

Fury - 4% Attack Speed becomes 8% with W active.
Feast - Reasonable sustain.
Savagery - Kog'Maw thrives off his basic attacks. Makes last hitting a little easier.
Secret Stash - A little more sustain. Don't be afraid to buy 2-3 health potions per back if you have the gold.
Merciless - Synergises well with Kog'Maw's R, which deals more damage to low health enemies.
Dangerous Game - A little sustain, nothing major. Kog'Maw tends to poke in bursts which doesn't make the most of Bandit.
Precision - Synergises with Kog'Maw's hybrid nature. Again, not major.
Stormraider's Surge - Gives a little escape and chase to an otherwise immobile champion.
Recovery - A little sustain, nothing major.
Tough Skin - A bit of protection. You're squishy. Those minion AA's soon add up!

It isn't Season 5 anymore. Stop building Trinity Force.

Start with Doran's Blade for the sustain and extra damage. Cull doesn't give enough sustain and you're not looking to rush any items that bad.

First back should be around 1050g. You shouldn't be trying to trade too heavily early on (and definitely no all-ins) so you should last that long by farming safely and asking your support to kindly stop rocket-grabbing the enemy Graves. If you go back before the 1050g mark sacrifice the vision ward and the pot's but make it a priority to stay alive long enough for the pickaxe! Otherwise you're coming back to lane with nothing. If you have enough for Blasting Wand, you can afford to wait for the extra 25g for pickaxe.

Before we look at the main items let me just breakdown Kog'Maw's ability scaling.

Q - Deals Magic Damage scales with AP (Passive scales with AS)
W - Deals magic Damage, scales with AD and AP
E - Deals magic Damage, scales with AP
R - Deals Magic Damage, scales with AD and AP

We're building Hybrid for max damage.

Guinsoo's Rageblade It's an incredible item on Kog'Maw! Adds moderate amounts of AD and AP, but the passive is what we're really after!

UNIQUE Passive: Basic attacks grant +8% Attack Speed, +3 Attack Damage, and +4 Ability Power for 5 seconds (stacks up to 8 times, melee attacks grant 2 stacks). While you have 8 stacks, gain Guinsoo's Rage.

Guinsoo's Rage: Basic attacks deal bonus magic damage on hit equal to 20 + 15% of bonus Attack Damage and 7.5% of Ability Power to the target and nearby enemy units.

With Kog'Maw's W you'll be pumping out AA's and hitting 8 stacks in no time. So let's do the number on this. As well as 30 AD and 40 AP, at 8 stacks you'll be getting:

+64% Attack Speed (+128% with W active)
At least 78.5 Attack Damage, even more with AD scaling. (24 + 30 + 20 + 15% of bonus AD = )
At least 75 Ability Power (40 + 32 + 7.5%)

One more time - +64% AS, 78.5+ AD, 75+ AP
Guinsoo's costs 2800g

That is why it's your first item!


Hextech Gunblade - 40 AD, 80AP, 15% Life Steal and a 150 + 40% AP active which slows. Ideal for punishing anyone trying to dive you.

Runaan's Hurricane - 40% AS, 30% Crit Chance, 5% movement speed and the passive:
UNIQUE Passive - Wind's Fury: When basic attacking, bolts are fired at up to 2 enemies near the target, each dealing (25% of Attack Damage) physical damage. Bolts can critically strike and apply on hit effects.
UNIQUE Passive: Basic attacks deal an additional 15 physical damage on hit.

You should be looking to push towers now and with Runaan's you can eat your way through minion waves.


Wit's End - 40% AS, 40 MR, 40 Bonus Magic Damage on hit (applies to Runaan's passive bolts) and takes 5 MR from enemies (stacks up to 5 times, so that should almost instantly be 25 MR gone).

Lord Dominik's Regards - Your new Last Whisper item. Not many champions are going to have less health than you.

+40 Attack Damage

UNIQUE Passive - Giant Slayer: Grants up to +15% physical damage against enemy champions with greater maximum Health than you (+1.5% damage per 50 Health difference, maxing at 500 Health difference).
UNIQUE Passive - Last Whisper: +40% Bonus Armor Penetration.

Congratulations, you can now eat tanks.


OPTIONALS

Rapid Firecannon - Only if you need the extra range (i.e. being bullied by Caitlyn or Tristana).
Youmuu's Ghostblade - That active :o
Void Staff - Surprisingly good. Shred MR Tanks.
Blade of the Ruined King - Life Steal and the active is great for baiting enemies who THINK they can finish you off.
Phantom Dancer - Not bad on Kog. We're not really building for crits. The passive is a "nice to have" not a "must have."

Q is levelled first for the scaling passive, Attack Speed, which by proxy makes your W better (scale 2 abilities for the price of one?). If you are getting bullied and need to farm from range there is an argument for maxing W first for the extra range, but maxing Q negates a lot of the early game weakness associated with Kog'Maw. Attack speed increases with W active become 30/40/50/60/70 as opposed to 15/20/25/30/35. This is important as you can rack up the stacks on your Guinsoo's Rageblade quicker.

Passive - Icathian Surprise

When you die just run at the enemy. Prioritise low health targets. Aim to get enemies who can't get far enough away as the damage is (small) AoE. Job done.


Q - Caustic Spittle

Skillshot sort-of-nuke. Can be used in an emergency to last hit early on in lane, especially under tower, but try to avoid due to mana cost (60). Especially later on it can be used to strip the armor and magic resist from tanks/supports before unleashing your W. Actually does a reasonable amount of damage with this build.


W - Bio-Arcane Barrage

This is your bread and butter. Turns your attack range from mediocre to good, although don't think you can outrange Jinx's Zap. The attack speed on this is what we have it for. Use when possible in almost any situation due to reasonble mana cost and low cooldown. Acceptable to use when farming under your own tower.

E - Void Ooze

Mostly used for the slow. Great range on it. Slow enemies from advancing on you, diving you escaping from you and can be a reasonable all-in initiation.


R - Living Artillery

High range execute. Does MASSIVE damage to low health enemies. Don't get carried away by the low cooldown, it can eradicate your mana in no time. Also don't bother poking with it in lane, the probability of hitting with it when the enemy isn't running in one direction (away from you) is significantly lower. That said, feel free to spam it before backing.

Basic all in combo: E, Q, W, R (Slow, (flash if ABSOLUTELY necessary to avoid hitting minions) Shred Armor and MR, Vomit Uncontrollably, Execute). Feel free to break that out into E + W, E + Q, Q + E, W + R combos etc...

As I play with Kog more (Get it???) I may add more sections (I may not), especially Strong/Weak Against and support synergies. I hope you enjoy this guide and feel free to tell me I'm wrong. Just don't downvote this guide until you've tried it for yourself.