Class-II terpene synthase that synthesizes 8-hydroxy-copalyl diphosphate. Involved in the biosynthesis of cis-abienol, a labdane diterpene that can be used as synthesis precursor of ambergris substitution fragance products. (2E,6E,10E)-geranylgeranyl diphosphate + H2O = 8-hydroxycopalyl diphosphate Secondary metabolite biosynthesis; terpenoid biosynthesis. Expressed specifically in the secretory cells of the glandular trichomes. The Asp-Xaa-Asp-Asp (DXDD) motif is important for the catalytic activity, presumably through binding to Mg(2+). The expression of both CPS2 and ABS is necessary and sufficient to catalyze the biosynthesis of cis-abienol from geranylgeranyl diphosphate in a heterologous system. Belongs to the terpene synthase family.