This is my first build, and I'm pretty new here, so I'll keep things simple. Kog'Maw rapes with AS, AD, and a little bit of AP. In case you couldn't tell, my recommended items are 2-3 Phantom Dancers, 1-2 Hextech Gunblade(s), 1 Madred's Bloodrazor, and a Berserker's Greaves. (You can interchange a Gunblade with a Phantom dancer, or vice versa to suit your needs.) With this build, you'll have just enough attack damage, attack speed, and ability power to destroy everything. Hope this was helpful in your quest for domination!