Complex sentence: The "Metamorphosis" EP, issued in September 1999, showcased Ulver's new electronic sound, delving into what would become the foundation for all future records, thus acting as a musical trailer for "Perdition City".
Split into simpler sentences: The "Metamorphosis" EP, issued in September 1999, showcased Ulver's new electronic sound, delving into what would become the foundation for all future records. Thus, acting as a musical trailer for "Perdition City".