Complex sentence: Niflheim launches an attack on the kingdom in an attempt to kill Regis and Noctis, and in the ensuing invasion the queen of Tenebrae is killed by General Glauca.
Split into simpler sentences: Niflheim launches an attack on the kingdom in an attempt to kill Regis and Noctis. In the ensuing invasion the queen of Tenebrae is killed by General Glauca.