It would be more logical for the second Mafia team to eliminate competitors now, if they still have any hopes in this game.
Well, the execution of Haven is a perfectly acceptable option for me. I trust the Master, and I believe that someone needs to be executed.
However, if Haven is indeed a loyal player, what about the option of imprisoning him in an ice prison? In that case, he won't be able to help the evil Warlock, and if she dies, he can be released and we'll get a second Fortress archer + defender. Although this idea is quite absurd and probably has some drawbacks, but overall, what do you think about it?

