I saw this suggestion a while back.
I think Mastermind should either have a day ability that allows him to choose when he is immune to checks (3 uses) or just be permanently immune to checks. Also, the amount of uses for the ability carries over to new converted MM, and it tells all unseen in chat that ‘The Mastermind will be immune to checks tonight.’ Mastermind should only be found via social deduction, not mechanics as he is such an important class. Furthermore, I think the assassin promoted to Mastermind feature should be available n4 as most Masterminds are killed n4 if they are killed before end game.