Survivability is not an option for me. I think if tank and support deal a good job there wont be any problem for Kog'Maw.
I built this guide for teams and not for public gaming :D

Thats my opinion. But you could change Wit's End with a survivabilityitem too.

Yeah i first was confuse about that guide and dont read it complete when i saw Karthus with Smite and Revive. Sry my fault.

Good build in general, but you should replace rylai or nashor's with a survivability item, like banshees or GA.

no i posted right link i just forgot to name it. FIXED

Thanks for your comment. Yeah I dont know how to do that. Thanks for that link i will edit it tomorrow.

Its very well done, good hybrid build, but i would suggest using some color, and coding, if you don't know how here's a guide How to make a guide.