Build your building's until you get the genetic mutator and the grinder, then build a bunch of slave minor vehicle things once you have lots put them all on one patch of ore. when all the minors come out use the genetic mutator on them. they will all turn into brutes. then just order them all to go into the grinders, LOTS OF MONEY or you can take all those brutes and put them into the enemys base, either way works. and as for your slaves they will be replaced after they are mutated.