If you pay a little attention, you will see that Warmog Blood Armor is one of the most popular equipment at the moment.
Basically, the team playing around Kog’Maw will be Guardian – Shooter at the beginning of the game and combined with Mutation in the later stages.
As for equipment options, Guinsoo’s Rageblade is a must-have item for Kog’Maw.
For front-line units, Garen is the champion that needs to be equipped the most with two main items: Warmog’s Blood Armor and Thorny Cloak.
At level 6 onwards, you should activate the Mutation effect with Malzahar to make Kassadin and Kog’Maw stronger.
If you can own the Mutation Seal, you can combine it with Garen if you possess effects such as Mutation Evolution or Enhancement Technology.
As for hextech upgrades, Mutant Evolution is the best choice for this squad.
Martin 
Samuel 
Eliana