Multifunctional enzyme that converts oxidosqualene to lupeol, bauerenol, alpha-amyrin, taraxasterol, psi-taraxasterol, multiflorenol, alpha-seco-amyrin and beta-seco-amyrin. (S)-2,3-epoxysqualene = alpha-seco-amyrin (S)-2,3-epoxysqualene = beta-seco-amyrin Belongs to the terpene cyclase/mutase family.