συγκατεργάζομαι
From LSJ
English (LSJ)
A help or assist any one in achieving, τῷ Κύρῳ τὴν βασιληΐην Hdt.1.162, cf. E.Or.33; τὸ πᾶν ξ. Th.1.132: c. dat. only, aid, assist, Hdt.2.154, 8.142. 2 help to conquer a country, Plu.Pyrrh.18. 3 join in murdering, E.HF1024 (lyr.).