This is a guide for Kog'Maw the Mouth of the Abyss
Please try out and the build before commenting or voting and to always remember what works for one person might not for others so try other guides.

Hey everyone this is my first time making a guide so bear with me here editing will come along.

This build is strictly for AP kog'maw I personally have perfected this build as much as possible. One thing I can tell you is that kog'maw will die as AP and I believe is my best friend either way.

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 level) true damage to surrounding enemies.


Chances are you are not going to kill anyone with this.

This skill does not deal significant damage and is not easy to lane, but just run up to people and blow up on them anyways.


Caustic Spittle

Passive: Increases Attack Speed by a %. Active: Kog'Maw launches a corrosive projectile which deals magic damage corrodes the target's armor for 4 seconds.

Spell Effect
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 per ability power) magic damage and reduces the target's armor by 5/10/15/20/25.


The spell is not bad. It has 0.7 ability power ratio and deals the same damage as Void Ooze but with twice the spam-ability and a bit less range. This spell is surely better early on when you have low ability power compared to Bio-Arcane Barrage.


Bio-Arcane Barrage

Koh'Maw's attacks gain range and deal a percent of the target's maximum health as magic damage.

Spell Effect
Kog'Maw's attacks gain 140/180/220/260/300 range and deal an additional 2/3/4/5/6% (+.01 per ability power) of the target's maximum Health as Magic Damage (Max: 100 Damage vs Monsters). Lasts 6 seconds.

The ability power ratio means the skill deals an additional +1% of target's max hp for every 100 AP.

Positives

- This spell can help your team take down a tank, but generally it is not a good idea to be at the front lines.

- Living Artillery takes 6 seconds to 'cooldown', while this spell has a duration of 6 seconds. Means that you can use Bio-Arcane Barrage to harass while conserving your mana cost.

Negative

- When you are attacking, you are not casting. This means that you are not bombarding their opponents!

- Using this spell will also push you out of hiding.


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.

Spell Effect
Kog'Maw launches ooze which deals 60/110/160/210/260 (+.7 per ability power) magic damage to enemies it passes through.
Additionally, it leaves a trail which slows enemies by 28/36/44/52/60% for 4 seconds.

Our bread and butter early game farming ability.
Has the same utility as Mega Adhesive can be used very offensively when combined with lving Artillery.


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.

Spell Effect
Kog'Maw fires artillery from a great distance (1400/1700/2000). After a short delay, the artillery falls dealing 80/120/160 (+.3 per ability power) 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 250).

Champion Damage:
Spell damage to hero: 200/300/400
Ability Power Ratio : 0.3 + 0.3 * 1.5 = 0.75
Note: From testing, it seems like the ability power bonus is not added into the bonus damage

This is the best skill that Kog'Maw have, this build puts a lot of focus bring this skill's potential to the max.

Living Artillery is very good at forcing your opponent to move and not fight. If a ranged champion is harassing your team. Fire at their current location and force them to kite/dodge it, continuing this allows your team mates to approach the target. Once your teammate reaches the target, he will have to choose between fighting or fleeing.

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Application of Living Artillery:
http://en.wikipedia.org/wiki/Artillery#Application_of_fire
Here are some of the things you can do with Living Artillery,

Supporting Fire:
- Always always support your tank with living artillery
- Due to the awesome attention seeking skills of your tanks, you are able to bombard freely over enemy threats whom are threating to your tanks
- If the tank is the type that makes people clump toward him (ie Shen), fire as much spitball as possible

Defensive fire:
- As your team is moving backward / retreating, you should cast living artillery between you and the enemy forcing them to either dodge it or tank it. Cast Void Ooze to slow opponent down. All this while kiting backward toward your base.

Harassing fire:
- a random number of shells are fired at random intervals, without any pattern to it that the enemy can predict
- Use this at towers to harass the opponent and give them shell shock.

Counter-battery fire:
http://en.wikipedia.org/wiki/Counter-battery_fire
Summary: KILL THE OTHER KOG'MAW
- Always and Always aim for the other Kog'Maw when your allies are not in immediate danger. This will stop the enemy Kog'Maw from drolling all over your team.

(b)(color=green)Pros:(/color)(/b)
- LIST OF PROS
- Super Long range
- Strong Treat in team fights after level 11
- Can not hard carry a team
- Best vs squishy


(b)(color=red)Cons:(/color)(/b)
- LIST OF CONS
- An intimate relationship with Smart Cast [ R ]
- Less effective verse a healing team and tanky team.
- Can't kill towers