Complex sentence: But she is ultimately defeated due to a ploy used by Princess earlier that day: she kissed Sister Cindy but her lipstick contained poison which, combined with some wine she has drunk, kills her.
Split into simpler sentences: But she is ultimately defeated due to a ploy used by Princess earlier that day. Princess had kissed Sister Cindy with poisonous lipstick, which, combined with some wine she has drunk, kills her.