Complex sentence: That night, Blossom has her girls serve the Lions, and Silk serves Brass; at Blossom's signal, the girls use hidden weapons in their mouths to poison many of the Lions and then join with Blossom as the Black Widows.
Split into simpler sentences: That night, Blossom has her girls serve the Lions, and Silk serves Brass. At Blossom's signal, the girls use weapons hidden in their mouths to poison many of the Lions and they join with Blossom as the Black Widows.