Greetings, all. This is my first build, so please comment and vote. No troll voting, if you don't mind.

The purpose of this build is to utilize Kog'Maw's inherent attack speed, HP shredding from Bio-Arcane, and armor/MR lowering from Caustic Spittle in order to quickly render opponents vulnerable for you and your team.

Items are built for on-hit effects to weaken the opponent, as well as get attack speed to the 2.5 cap.
The Black Cleaver lowers armor,
Malady lowers MR,
Madred's Bloodrazor is essential on Kog'Maw, and shreds HP, and
Frozen Mallet slows with each hit.

This is most viable in teamfights. It may need improvement, so feel free to comment.
Zerglinator out.