Poisoner is always solid to use, since it’s tricky to confirm its existence.
Baron is out, it changes setup.
Scarlet Woman would be an amazing Mole bluff, since they could trick Demon into willingly dying, but it doesn’t work as a Plague Doctor effect. Out.
Spy can’t be bluffed by Mole, and is useless with Plague Doctor. Out.
The only Minion from S&V that isn’t incredibly public with its existence (and therefore works for Mole) is Witch, and Witch works well for a Plague Doctor as well, since it can be used by ST to curb aggro town who keep running the nominations.
Godfather and Assassin don’t work for Mole, and Assassin in particular is unfair to have for Plague Doctor. Out.
DA sounds good on paper until you realize that no town in this script can mimic its effect, so DA being in play would be known as soon as an execution failed. Out.
Mastermind actually works as a Plague Doctor ability where SW doesn’t, and can be used by Mole to get the Demon to willingly die if they’re clever about it.
Final three:
Poisoner
Witch
Mastermind
Pick two of those, they’ll work for you.