Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
mastermind [ˈmɑːstəmaɪnd] n (of plan) созда́тель(ница) m(f)
vt разраба́тывать (разрабо́тать perf)
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.