May be involved in the biosynthesis of ent-kaurene diterpenoids natural products such as oridonin, miltiradiene, eriocalyxin B and nezukol, known to exhibit antitumor, anti-inflammatory and antibacterial activities. Binds 3 Mg(2+) ions per subunit. Secondary metabolite biosynthesis; terpenoid biosynthesis. Expressed in leaves. 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.