In regards to the question of how Servalan was able to zap sample targets after marking Travis, an idea came to mind. Perhaps it can be set to "last marked, first killed" mode, allowing a person to select only the last marked target (and might work its way baack to the others if you keep it on longer). That might make more sense than directionality, and also have allowed Rashel to threaten Servalan without potentially killing everyone else.