Hey everyone and welcome to the Kog'Maw full build, this is my first build so feel free to leave any constructive criticism. For kog, he is a very good AD carry with all of his abilities scaling off of AP and his ult scaling off of AP and AD making having some AP in your build slightly helpful when you play AD
Boots + 3 Health Potions ~~~ Kogmaw is a very slow champion to start out with and unlike most other AD carries he has no escape/flash ability like how Graves has Quickdraw and Corkie has Valkyrie so he needs all the escapability he can get, and the potions help you to survive in lane longer.
Doran's Blade X2 ~~~ Doran's items are extremely useful for early game sustainablility and they provide everything you will need early game to help you win your lane.
Berserker's Greaves ~~~ Kogmaw needs attack speed to get the msot use of of his W so having the additional 20% attack speed is basicly a steroid for kogmaws damage output
Madred's Razor ~~~ Being the bottom laner that kogmaw is, he will be needing some armour early game along with him needing to have some attack damage. This item gives kogmaw all of that and plus its passive can proc to help you CS even better than before and help you outfarm the enemy AD carry.
Vampiric Scepter ~~~ This item helps kogmaw replace his dependance on health potions and helps sustainablility, nuff said ^w^
Bilgewater Cutlass ~~~ This item gives kogmaw everything he needs from Attack Damage to Life steal and a free EXHAUST for the items Unique Active, which will later be turned into a Hextech Gunblade.
Infinite Edge ~~~ Crits are a very important part of any AD carry's role and doing more damage in each crit helps ALOT, this items is just standard in any AD carry's build, and it is completely clear why.
Phantom Dancer ~~~ movement speed, attack speed, and critical strike chance, what more could you ask for out of an item :O
Madred's Bloodrazor ~~~ This item is purely amazing on kogmaw once he has his Phantom Dancer because ontop of having his W, this item just adds to all the damage output he does on every auto attack, it is impossible for me to play Kog without this item.
Hextech Gunblade ~~~ As previously stated Kog needs ability power, and this item gives him just that, all the ability power that kogmaw will need and attack damage to complement it :D
Last Whisper ~~~ All AD carry's MUST have this item because late game many people will have armour that will try to stop your attacks from hitting them to the fullest so with this armor wont affect you as much.
Greater Mark of Desolation ~~~ it just purely helps kogmaw early mid and late game to stop enemies that stack armor from taking longer for kog to kill
Greater Seal of Resilience ~~~ these will help you sustain your lane in early game as well as keep your survivability late game
Greater Glyph of Shielding ~~~ I chose this item over the flat magic resist glyphs because early game you really wont need too much magic resistance since all you'll be doing is taking hits from an AD champion.
Greater Quintessance of Swiftness ~~~ kogmaw really has no escapability when ganks come around so having the extra movement speed helps him get away from those situations as well as chase down enemies and go in for the penta ;)
OFFENSIVE ~~~ I put the standard 21 points into the offensive tree because you really cant deviate from that main build
DEFENSIVE ~~~ I put one point into the defensive tree to help kogmaw get a little extra health from summoner spell heal to help his surive ganks as well as going in for the tower dive and for the kill
UTILITY ~~~ I use a point to reduce the CD of Flash, 3 points into magic regen, and four into movement speed to help save mogmaw from many bad situations
Passive~~Icathian Surprise - Upon dying, Kog'Maw starts a chain reaction in his body which causes him to move faster and detonate after 4 seconds; dealing 100 + (25 x lvl) true damage to surrounding enemies.
Q~~Caustic Spittle - Passive: Increases Kog'Maw's Attack Speed. Active: Kog'Maw launches a corrosive projectile which deals magic damage and corrodes the target's Armor and Magic Resist for 4 seconds.
Passive: Increases Attack Speed by 10/15/20/25/30%.
Active: Kog'Maw launches a corrosive projectile which deals 60/110/160/210/260 (+0.7) magic damage and reduces the target's Armor and Magic Resist by 5/10/15/20/25 for 4 seconds.
W~~Bio-Arcane Barrage - Kog'Maw's attacks gain range and deal a percent of the target's maximum health as magic damage.
Kog'Maw's attacks gain 130/150/170/190/210 range and deal additional magic damage equal to 2/3/4/5/6% (+0.01)% of the target's maximum Health (Max: 100 Damage vs Monsters). Lasts 8 seconds.
E~~Void Ooze - Kog'Maw launches a peculiar ooze which damages all enemies it passes through and leaves a trail which slows enemies who stand on it.
Kog'Maw launches ooze which deals 60/110/160/210/260 (+0.7) magic damage to enemies it passes through.
Additionally, it leaves a trail which slows enemies by 20/28/36/44/52% for 4 seconds.
R~~Living Artillery - Kog'Maw fires a living artillery shell at a great distance dealing damage and revealing targets. Additionally, multiple Living Artilleries in a short period of time cause them to cost additional mana.
Kog'Maw fires artillery from a great distance. After a short delay, the artillery falls dealing 80/120/160 (+0.5) (+0.3) magic damage and reveals targets for 4 seconds (deals 150% bonus damage to Champions).
Each subsequent Living Artillery in the next 6 seconds costs 40 additional mana (Max 200).
Flash ~~~ unlike most AD carries kog doesnt have a dash ability and that hinders him from making escapes, so it is mandatory to have this ability to save yourself every 4 minutes.
Heal ~~~ This gives you laning sustain, Survivablility, and tower-dive-ability, this is your holy water that will save you and trust me, it will :O
That has been my brief Kogmaw guide, If you like this build and it works for you please rate it up and comment with you success, and if you dont like it, please feel free to leave a comment in the bottom to tell me what you dont like about it and what i shoukd chance, thank you for reading, and go out there and dominate with The Mouth of the Abyss ;3