You have got all the essentials. I would get safer transportation anyway. After that it depends on you. General cost and longer defence lines are useful. If youre encountering ds and sm a lot maybe invest in antiair. You could begin working on marine upgrades if you want to play more gw and mos. Maybe get sm or blitz.
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Longer def lines and sky menace
thank you guys.
getting all the strategies and upgrading marines.
the current defense line distance is good thou, isn't it ? gets the job done
ps. how come i never got sky menace ? I'm 90% sure i used it couple of times x_x