Easy programming thing would be to allow guilds to fight those guilds closest to them in rank.
Something like guild rank +/- 1 then view threat lvl and if threat lvl +/- 100 then allow attack.
This would allow rival guilds to fight. Prevent lots of guilds ganging up and bullying one guild and still does a threat lvl check to make sure you simply don't over power the other guild opponent but have to fight them on fair footing.
You don't have to change any of your programming but add in a few checks and if/then optuons.