I am TheFrutzinator (AscL Frutz on EUW) and I am excited to show you this Kog'Maw guide
: The synergy with this item is really good, the passive combined with the attack speed is really strong on Kog'Maw. Also a good rush considering it has lifesteal.
: Attack Speed on boots, pretty standard on ADC's and works well with his w.
: The Black Cleaver is not really a standard item for ADC's but I think this item fits Kog'Maw really well considering he already is a tank shredder. This item will make you kill tanks but also squishies fairly easily.
: It gives you a lot of attack speed which is always appreciated on the new Kog'Maw but also gives you some magic resist and most importantly the 42 on hit damage. You will also shred tanks easier because of the passive that steals Magic Resist.
: Bloodthirster gives you a lot of AD which is great considering you don't have that much with this build. It also gives you the survivability with the lifesteal and passive shield.
: The item gives AD and AP which is great for your w, and gives a lot of attack speed when you attack a couple of times, this item also applies on hit effects when the passive is active. The aoe dmg is also appreciated in teamfights.