FAD-dependent oxidoreductase; part of the gene cluster that mediates the biosynthesis of the sesterterpenes ophiobolins, fungal phytotoxins with potential anti-cancer activities (PubMed:27116000). The first step of the pathway is performed by the sesterterpene synthase oblA that possesses both prenyl transferase and terpene cyclase activity, converting isopentenyl diphosphate and dimethylallyl diphosphate into geranylfarnesyl diphosphate (GFPP) and further converting GFPP into ophiobolin F, respectively (By similarity). Other sesterterpenoids (C(25) terpenoids) are found as minor products of oblA (By similarity). The cytochrome P450 monooxygenase oblB then catalyzes a four-step oxidative transformation of ophiobolin F to yield ophiobolin C (PubMed:27116000). The FAD-dependent oxidoreductase oblC might be involved in a later oxidation step that produces ophiobolin A (Probable). Secondary metabolite biosynthesis; terpenoid biosynthesis. Belongs to the beta-cyclopiazonate dehydrogenase family.