Mastermind preys on the Heroes’ (and players’) minds. When battling him, it is especially dangerous to be alone, as that is when a Hero is the most vulnerable to believing the illusions Mastermind creates. Whenever there’s an Overflow, lone Heroes take damage. All Threats affect Heroes starting their turn alone in their Location, luring, confusing, and trapping them. Mastermind creates illusionary duplicates of himself, adding Crisis tokens to Locations which the Heroes must defeat before they are able to attack him. His BAM effect damage Heroes who fail to guess correctly the Move number of his next Master Plan card, a task that is further complicated by the fact that his devious plans are constantly reshuffling his deck.
https://www.kickstarter.com/projects/cmon/marvel-united-x-men/posts/3180994