Sentinels are the "sub-admins" of the server. They have the ability to enter Spectator Mode in order to fix issues or help players, as well as to enforce the rules of the server. Sentinels have the ability to send rule-breakers to Purgatory, as well as mute and ban if needed.
While Sentinels do play on the server, they are not allowed to siege other players (due to the sensitive information their job requires them to be privy to.) However, Sentinels may defend their own Nation during a siege. Also, Non-Sentinel members of a Sentinel's Nation are not restricted from sieging.
Sentinels can be identified in-game by their purple names in the chat window.
Current List of Sentinels