This idea is to provide a response to possible (ab)use of Sentinel tag to attack a smaller fam inside their core, and allow small fams to clear big fams from their core without canceling NW protection.  The Guardian tag would provide a 50% attack bonus (100% attack bonus against Sentinels).  A player with Guardian tag is only permitted to attack targets within say 10 ticks? of fam's home system.  Again, attacks committed by Guardians would not cancel fam NW protection.  This would allow small fams the ability to clear big players, only fair since big fams have to clear small players with Sentinels.