The fourth studio album by the Norwegian black metal band, originally released in March 1999. This release featured keyboardist Mustis and the clean vocals of ICS Vortex, as well as the departure of long-time drummer Tjodalv, guitarist Astennu, and bassist Nagash. Musically this was a departure for the group. The music's overall feel is faster and darker with more emphasis on the keyboard lines versus the slower, more riff-heavy approach of previous albums. The band attributes this to Astennu's due influence, as his Carpe Tenebrum project at the time had a very similar musical direction.
Track Listing: 1. Reptile - Dimmu Borgir (5.17) 2. Behind the Curtains of Night Phantasmagoria - Dimmu Borgir (3.21) 3. Dreamside Dominions - Dimmu Borgir (5.15) 4. United in Unhallowed Grace - Dimmu Borgir (4.23) 5. The Promised Future Aeons - Dimmu Borgir (6.52) 6. The Blazing Monoliths of Defiance - Dimmu Borgir (4.39) 7. The Insight and the Catharsis - Dimmu Borgir (7.17) 8. Grotesquery Conceiled (Within Measureless Magic) - Dimmu Borgir (5.1) 9. Arcane Lifeforce Mysteria - Dimmu Borgir (7.03)