Complex sentence: In the end Lann and Reynn know the truth that Lady Lusse and Mister Rorrik was died for many years after their bodies used as a vessel and they both sacrifice themselves to sent Brandelis back and split all the worlds.
Split into simpler sentences: In the end, Lann and Reynn learned the truth: that Lady Lusse and Mister Rorrik had been dead for many years. Their bodies had been used as vessels, and they had both sacrificed themselves to send Brandelis back and split all the worlds.