Complex sentence: Before Chucky begins the incantation, which Tiffany distracts Chucky by kissing him, but Tiffany pulls the knife out of Chucky's pocket, and stabs him in his back.
Split into simpler sentences: Before Chucky begins the incantation, Tiffany distracts Chucky by kissing him. Then she pulls the knife out of Chucky's pocket, and stabs him in his back.