If 300 whatchamacalits are spores, then you don't need to farm. Main missions give you 200 spores on completion. If you've finished them, then I guess you're stuck, though.
Shakh -- I rarely use THELs, they're too brittle. Missiles are good against motherships, especially when they are fully upgraded, because the ships tend to clump, so you can kill all of them at once.
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