Envoy Curisers
After playing for several hours this morning the first suggestion I would make is upgrading the undermine ability for the envoy cruisers. The ability to undermine using just one cruiser is pointless because the loyality of the planet just goes back up after a few seconds. As it stands now it seems that I need a fleet of 5 or more cruisers to take down a planet.
This situation does not make diplomacy an alternitive to military force.