Kog'Maw in this build is an anti-tank, or a DPS. Kog'Maw is mainly anti-tank because of caustic spittle(which lowers defense), bio-arcane barrage(which deals a percentage of the enemies max HP as magic damage. Bio-arcane barrage with madred's bloodrazor. Because of caustic spittle's passive, which gives attack speed, Kog'Maw can be a DPS. Note Kog'Maw is VERY item reliant.

The reasons i choose to get doran's blade first is because of how cheap it is. A head 100 hp with damage and bit of lifesteal gives that edge that might give you first blood. After that, i straight away get a beserker's greaves, as Kog'Maw's speed is quite bad. Beserker's greaves works with caustic spittle, so by the time you are level 7, you should have beserker's greaves 25% attack speed to compliment the 15% attack speed. This should give a good 40% attack speed boost. Only take madred's razor because the bloodrazor cost to much and is

Right at level 6, you want to get the golem buff so that the mana cost of