[Paul1980au]

Im guessing that by closing off warp points you can attack 1 system at a time. In terms of affecting productivity well an intel project to attack his economic lines is a good idea. Planet buster attacks with well shielded cruisers with rapid engines to attack planets with planet buster and plague bombs to destroy population and facilities. What you want to do when you attack is to capture planets (troops if possible) that have ship building and mineral extraction facilities to cut off his lifelines.