A Jailkeeper (or Jailer)'s Night Action is one that protects its target from kills, but also Roleblocks its target. Unlike Doctor, Jailkeeper's protection extends to stopping every kill that would resolve on the target by default.
Because it is a combination Doctor and Roleblocker, Jailkeeper has a myriad of uses while not allowing broken combinations or exactly confirming anyone as Town or scum. Thus, it has risen to prominence as a very popular power role.
Because it is a Roleblocker, Jailkeeper is never allowed to self-target.
An Alien is a similar role (which is also Normal), blocking its target and protecting its target from actions (not just kills). This variant has rarely been called "Jailkeeper" in the past, but nowadays has a different name.
A Jailkeeper that simultaneously blocks and protects their target is considered Normal on mafiascum.net, provided that any mutual blocking scenarios are planned for during review. Any role that receives results (such as Tracker or Watcher) but is blocked as a result of being targeted by a Jailkeeper should receive a "no result" message, rather than told their target didn't go anywhere or nobody visited their target. A Jailkeeper cannot stop a Strongman from committing a kill (regardless of who they target), and does not prevent other players from targeting their target with non-killing actions (e.g. if a Watcher and Jailkeeper target the same player, the Watcher will see the Jailkeeper's action).
Use and Power
By combining the best of Doctor and Roleblocker, Jailkeepers are always solid mid-level power roles for Town that are safe for combining with many other power roles. Mafia Jailkeepers are not unheard of, but overkill for many games as they can generally get by with either a Doctor or a Roleblocker. (Note, however, that it's fairly common for Mafia to claim to be a Jailkeeper when they're actually a Roleblocker; this is hard to disprove without a Role Cop and makes the role sound more townsided.)
Jailkeepers become much more powerful when there's only one anti-Town player left; blocking a player proves that they didn't perform the nightkill that night, and thus if the nightkill actually happens, the Jailkeeper's target must necessarily be Town. This gives the role a considerably more investigative flavour, and is normally the best way to use the role when you get the opportunity (unless preventing a kill is necessary to avoid losing the game then and there). As such, it's normally unwise to put a Town Jailkeeper in the same game as a Town Tracker (another commonly seen role which becomes much more powerful when the Town is doing well), as it creates a large amount of positive feedback and thus makes the game very unstable and hard to balance.
A side effect of the Jailkeeper being more powerful when there are few anti-Town players is that it's more powerful in games with few players, full stop (an effect that's amplified by the fact that in a small game, both the blocking and saving abilities are considerably easier to aim). In a large game, a Jailkeeper is substantially weaker than a Cop, but experiments in 9-player (i.e. Micro) games have shown that at that game size, the two roles are roughly equal in power. It's important to take this into account when balancing a game.
Sample Role PM
- Welcome, [Player Name], you are a Town Jailkeeper.
- Each night, you may jailkeep a player in the game by sending a PM to the mod. You will simultaneously roleblock that player, and protect that player from any number of nightkills.
- You win when all threats to the town have been eliminated and there is at least one town player alive.