He has an encyclopedic knowledge of everything related to comics, cards, and science fiction. He only owns one t-shirt, which smells of canned cheese and cherry coke. Furious at how little his lifetime collection of comics and games are worth, he devised a genius plan to inflate the prices of all comic and card items by creating a monopoly.
Each mastery level adds another card to the cardpool for defeating Milton. Each of the bronze, silver, and gold mastery levels unlocks a new card, while it takes all three diamond and onyx levels to unlock a single card.