Sesquiterpene synthase that catalyzes the cyclization of farnesyl diphosphate (FPP) into multiple products, including germacrene D, beta-copaene, beta-cubebene, (+)-sativene and cubebol, a natural sesquiterpene alcohol used in the food industry for its cooling and refreshing taste. Terpenoid hydrocarbons resulting from cyclization of farnesyl diphosphate are intermediates in the biosynthesis of biologically active compounds such as antibiotics, toxins and pheromones. (2E,6E)-farnesyl diphosphate + H2O = cubebol + diphosphate (2E,6E)-farnesyl diphosphate = beta-copaene + diphosphate (2E,6E)-farnesyl diphosphate = beta-cubebene + diphosphate (2E,6E)-farnesyl diphosphate = (+)-sativene + diphosphate Binds 3 Mg(2+) ions per subunit. The Asp-Asp-Xaa-Xaa-Asp/Glu (DDXXD/E) motif is important for the catalytic activity, presumably through binding to Mg(2+). Belongs to the terpene synthase family.