I think there should be a ship that is like the DEATH STAR from star wars that will planets planets and any kind of ships. Another MOD WOULD BE a defensive satillites around the planet that would attack anything that is hostile to them like in the series STARGATE ATLANTIS when the wraith hive ships were comeing and mcay got the defensive satilite up and destryoed a hive ship. and in the book HALO: FALL OF REACH where the only thing keeping the covenant to destroy reach is to destroy the defensive cannons. once one is destroyed the shield will be disabled and they can get thru to the planet.