Terpene cyclase; part of the gene cluster that mediates the biosynthesis of the neurotoxin verrucosidin, a methylated alpha-pyrone polyketide that inhibits oxidative phosphorylation in mitochondria and thereby causes neurological diseases (PubMed:34093475). The carbon backbone of verrucosidin is synthesized by the HR-PKS verA, and further modified by the other verrucodidin cluster enzymes (Probable). Secondary metabolite biosynthesis; terpenoid biosynthesis. Mycotoxin biosynthesis. Belongs to the membrane-bound ascI terpene cyclase family.