When the prophet Malzahar was reborn in Icathia, he was led there by an ominous voice which thereafter anchored itself to his psyche. From within, this voice bestowed upon him terrible purpose, and though Malzahar was no longer tormented by its call, the voice did not cease its unrelenting summons. This baleful beacon's gentle flicker -- now fastened to Runeterra -- drew forth a putrid beast that ambled across a threshold it did not understand, widening a fissure between the spaces which were never meant to meet. There amongst the haunting ruins of Icathia, Kog'Maw manifested in Valoran with unsettling curiosity. The spark which led him to Runeterra teased him still, urging him gently towards Malzahar. It also encouraged him to familiarize himself with his new environment, to the stark horror of everything he encountered on his journey.

The enchanting colors and aromas of Runeterra intoxicated Kog'Maw, and he explored the fruits of the strange world the only way he knew how: by devouring them. At first he sampled only the wild flora and fauna he happened across. As he traversed the parched Tempest Flats, however, he came upon a tribe of nomads. Seemingly unhampered by conventional rules of physics, Kog'Maw consumed every nomad and any obstacles they put in his way, amounting to many times his own mass and volume. The most composed of his victims may have had time to wonder if this was due to the caustic enzymes which stung the ground as they dripped from his gaping mouth, although such musings were abruptly concluded. When his wake of catastrophe reached the Institute of War, and enthusiastic Malzahar greeted him with an enticing prospect: taste the best Runeterra could offer...on the Fields of Justice.

This build is for killing heros over and over and over again. I am also new to making guides. Please leave comments on changes I should make.

When you engage an enemy you want to start by using Caustic Spittle on them and keep on throughout the encounter. After that you should press W and activate Bio-Arcane Barrage. When the hero starts running use Living Artillery slightly ahead of the path they are running along. With the swift boots, Phantom Dancer, Ghost, and Exhaust you should be able to catch any hero no matter how fast they are. If you die it should only be at the start. When you die make sure you chase the hero you were fighting to try and kill them with your Icathian Surprise. If you fight the Dragon or the Baron do the same thing except don't keep using Caustic Spittle. Instead spam Living Artillery on them. Do not attack either of them alone or first. Make sure you attack last of everybody so you don't get attacked.

If you want to farm you just have to run around using your ultimate. How else would you farm?

You just need to target one hero and try to hit as many heroes with your ultimate as possible. If you die run up and explode on as many heroes as possible.

Pros
Gets high attack speed.
Is extremely fast.
Ultimate is very strong.
Can easily kill heroes.

Cons
Can get killed easily if stunned or if 2 or more heroes attack you.
You need to be good at killing.
Is a moderately hard build to play as.

I highly suggest using ghost and exhaust. You can use flash instead of ghost and ignite instead of exhaust if you want.

For this character most of the things I buy are for attack speed. Why is for BIO-ARCANE BARRAGE. With more attack speed you can cram in more attacks well under that effect. His attack still hits about 200 and you have the armor penetration so that your attacks won't be blocked by armor. Those are really the only stats that matter.... well speed does to. As you can see though I get 3 speed items, so it's covered.

I get Doran's Blade so that I will be a little stronger and can get first blood in most of my games. You could skip this and get boots instead. I usually get the Boots of Swiftness for high speed. You could get Boots of mobility for running around really fast when not under attack. I still generally find that the Boots of Swiftness are much better. I buy Last Whisper for attack and armor penetration. Really that item should not be swapped out for anything. The Phantom Dancers are for high attack speed and critical. Plus the movement speed boost is helpful. You can switch these with whatever you find fits your play style. Then I get the Needlessly Large Rod to make my ultimate stronger. You could get an item that gives you higher ability power, but this gives you a lot and usually that is enough ability power. You should also buy the items leading up to it. If you get all of theses items you can sell Dorans Blade for another Last Whisper of a Phantom Dancer. Then change Needlessly Large Rod to a Rabadons DeathCap.

CAUSTIC SPITTLE
This skill hits them for a lot of damage. It also gives you an attack speed boost that stays permanently. Then its even better since it lowers their magic resistance.

BIO-ARCANE BARRAGE
Increases regular attack range. Also gives your attack a small boost.

VOID OOZE
Slows and hurts guys.

LIVING ARTILLERY
Delayed timing before it comes down and hurts targets. Fast cool down so you can use this over and over and over again. Acts kind of like a sniper.

Remember that this build is for hero killing. You can also do fine getting assists but it is much better to get the kills.

If you think this guide is good please vote +1 so that other people will see it. I have also added some other builds. these other builds should be pretty self-explanatory.