Catalyzes the cyclization of farnesyl diphosphate (FPP) to the sesquiterpene epi-isozizaene. (2E,6E)-farnesyl diphosphate = (+)-epi-isozizaene + diphosphate Binds 3 Mg(2+) ions per subunit. Can also use Mn(2+) and Fe(3+) but less efficiently, and other divalent cations such as Zn(2+), Fe(2+), Co(2+), Cu(2+) and Ni(2+) are nearly completely inefficient as cofactors. Sesquiterpene biosynthesis; epi-isozizaene 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.