Last Whisper and The Black Cleaver do not operate terribly well together. Given the two options I prefer the Black Cleaver for the following reasons:

- I've been playing AD/AS Kog'Maw since before his buff that made it a popular option; during that time I used Black Cleaver as it perfectly complimented the armor reduction passive of his Caustic Spittle at the time. It's an item I'm used to having on me and it's the one I still feel confident using as Kog'Maw to this day.

- Last Whisper is a selfish item while the Black Cleaver benefits the team. Last Whisper will increase the damage you yourself do against an armored foe. The Black Cleaver will whittle the armor of your enemy for everyone to wait against.

As for Malady, it'd be a terribly redundant item to have after already picking up Stark's Fervor. While having increased lifesteal on top of that of Stark's as well as the ability to add in extra damage per hit using its passive sounds like a really fun idea I think there are really better options out there for him.

Alas, this was my hesitation about providing a mastery build as I feel finding my way through it to still be a bit difficult. I see where you're coming from, and I agree. I've made the change accordingly; I appreciate the constructive feedback. :)

Sword of Divine isn't necessary. Make it Malady or Last Whisper.

great items. nice skill sequence. one thing i have an issue with however is that you left out 15% magic pen. now i know kogmaw is an AutoAttack dps carry, but think about it. bio arcane does magic damage in % health. Madreds does magic damage in % health. meaning all of the major damage coming from kogmaw is magic damage. now, is that extra 1 gold every 10 seconds really worth it? other than that, great guide +1