Plan B: Surround Dave with colonies, and then send massive waves of merchantmen into his planets to deprive him of resources by out trading him of everything!!!! mwahahah!
that's the odd thing. my 3 merchant fleets automatically went to one of his systems to sell food.... not sure i'm getting the hang on trading prices/tariffs..... or tax for that matter
i think his tariffs are at 0 whilst mine are around 3
