what reliable mastery can KogMaw take?

Warlords interacts with crit which KogMaw builds very little of.

Fervor is best on champions with AS steroids like Jinx, Cait and Draven. Kog can use it but the bonus AD benefits little towards his Q, W, and E.

Death fire scaling is weird. KogMaw gets so little AD from his items that neither single nor aoe will do much damage. Same goes for AP.

StormRaidersSurge is good but only conditionally. Provides nothing but MS and tenacity sacrificing lifesteal and damage. Only good with Lulu or Janna to shield you from damage

Thunderlords hahahahahahaha okay makes early game trading easy but late game fighting is pointless

Other defensive masteries are also useless.

Other ADC (maybe besides Corki) benefit from any of the masteries substantially more than KogMaw (trust me I've seen a TLD Draven before). So not only is KogMaw gated by his CDs, lack of crit interactions, mana, and mobility but masteries as well.