Complex sentence: In this adaptation, Galadriel narrates the Prologue, explaining the creation of the Rings of Power and the War of the Last Alliance, because she has first-hand knowledge of this history and actively participated in its events.
Split into simpler sentences: In this adaptation, Galadriel narrates the Prologue, explaining the creation of the Rings of Power and the War of the Last Alliance. Thus Galadriel narrates the Prologue, because she has first-hand knowledge of this history and actively participated in its events.