This "unorthodox" build is very similar to the recommended items presented in the store when one plays Kog'maw.

Build 1 (Heal + Flash):
Boots + 3 pots
2 Dorans
Berserker Boots
Madred's razors
dagger -> Malady
Recurve Bow-> Madreds
Zeal
IEdge
PDancer
Phage-> Frozen Mallet

Build 2 (Heal + Flash):
Boots + 3 pots
2 Dorans
Vamp Scepter
Berserker boots
Zeal-> PDancer
IEdge
Last Whisper
GAngel
BThirster

Build 1 Vs Build 2

Provide me with good analysis on which build is better. Thanks.

I like on-hit AD Kog WAY more than the simple AD.
Wits End, Malady, Madreds + Bloodthirster.
I esp. like the magic dmg. from Wits End, Malady and Madreds along with his passive. It gives him excellent dps. and can take down enemys fairly quickly, shredding their resistance, etc.
Berserkers, Wits End, Malady, Madreds, Bloodthirster or Black-Cleaver and lastly GA.
I tend to never go Phantom/Infinity because costs a little more. I like getting Wits for the resistance, Malady for magic shredding and all of Kog's abilitys are AP-Based, Madreds for the obvious reason, Black-Cleaver if they're stacking too much armor or Bloodthirster depending on the enemies...

ANYWAY!. I think build 1 would be better - Both Malady and Madreds are good on Kog, Frozen gives him a little more health and a nice slow.

Build 2 DOES work as well. It's all personal preference.

Personally, I prefer to play him as a glass cannon, so no phage, and GA only if my team doesn't do a good job protecting me, or if the other team has champions that can find and kill me easily.

The final build for me is as follows: Berserker Greaves, Infinity Edge, Phantom Dancer, Bloodthirster, Bloodrazor, Black Cleaver. This provides nearly maxed attack speed, and delivers two on-hit procs, as well as alot of crits and high sustain.

There are situations where I'd take a Last Whisper or Ghostblade over the cleaver, as well.

I guess I'd probably go with your build one over build two.

While I do love going Madreds on Kog, I am not sure it is worth it late game. I think IE PD really is the best dps you can get. Madreds is awesome mid-game as you chunk down their HP, but late game it doesn't hit as hard as IE. Maybe work it in late after IE PD? I love the madreds, but I just don't think it's worth it.

Not an expert, but why get MBR when your W is already magic damage? You are just gimping yourself if they build MR as opposed to the AD build.

I usually do the madred's late in the build, always after IE/PD.

As far as I know it does stack with Kog's W, too, so it's still worthwhile to use.