The Mason is a role that becomes exponentially more powerful the more players are Masons and the longer the game goes on. The role knows the identity of the Mason Leader and other Masons and is able to communicate with them at night.
Simply having Masons in the game allows for the Town to use a variety of otherwise extremely difficult to perform strategies revolving around their two or more automatically confirmed innocents.
A Mason's power is exponentially proportionate to the number of Masons and the length of the game. Having two or more confirmed innocents towards the end of the game helps to narrow down the Mafia immensely.
Claiming at the start of the game can be particularly useful as it saves Sheriffs and Investigators one or more night checks. The Mafia essentially has no way to deal with this as claiming Masons for themselves will only provoke the investigation of them. Even if the Mafia chooses to attack the Masons immediately because of this, the worst possible outcome is some free nights for the Investigative roles to pick up momentum for the Town.
Always leave the names of fellow Mason's using the Last Will feature if the Masons have yet to claim. This may prove to save the Masons' life or waste a Mafia kill that could have been dedicated to a more important investigative role. Use the Last Will by using the -lw command.
If there is a Mason Leader in play, take note of who he targets to recruit. If he survives that night the targeted person becomes a Mason by morning if they were a Citizen. Use this information if someone the Mason Leader attempted to recruit claims Citizen.
If a Mason doesn't appear at night meetings or on your list of Mason allies (at the top right) anymore but hasn't died, inform the Town immediately. This certainly means they were targeted and killed by the Disguiser.
Becomes Leader if alone - (Default: Off)
Along with the Spy, Mayor, and Executioner, the Mason is one of only four roles with no active night abilities.
Masons earn bonus points at the end of the game.
If the "Becomes Leader if alone" option is on, there will never be a Mason by himself in a game. If he does happen to random the role Mason, he will be promoted to Mason Leader.
When a Mason becoming Mason Leader, he'll get a new full amount of recruitment attempts, making it useful for the Mason Leader to Suicide if more recruitment attempts is needed.
When a Disguiser replaces a Mason or Mason Leader the victim won't disappear from the allies list, but the Disguiser won't be part of the Mason night chat.