Eidolon is an album by the German melodic black metal band Dark Fortress. This is the first album with Nassos as a real band member. Morean already appeared on Séance as the composer of the song Incide and the arranger of the string section used in the song While They Sleep. The reason he became a member was based on his musical and vocal abilities, his personage and dedication to extreme and dark music. He is responsible for the lyrical concept of Eidolon. This release is a concept album based on the Greek idea of an astral double, which is similar to the German concept of a doppelgänger.