Involved in the formation of muuroladienes. Produces mainly cis-muurola-3,5-diene and cis-muurola- 4(14),5-diene, but also smaller amounts of gamma-cadinene and alpha-cadinene. (2E,6E)-farnesyl diphosphate = cis-muurola-3,5-diene + diphosphate (2E,6E)-farnesyl diphosphate = cis-muurola-4(14),5-diene + diphosphate Binds 3 Mg(2+) ions per subunit. Secondary metabolite biosynthesis; terpenoid biosynthesis. 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.