Easily one of the most 'old school' Black Metal albums to be released in the last few decades. While many bands that worship the classics 'sound' old, XI actually feels old. Listening to this album is like discovering some lost gem from the early 90s. I hear echoes early Rotting Christ and Samael (especially Blood Ritual), with some Brazilian weirdness and Zé do Caixão (Coffin Joe) movie atmospheres. Highly recommended.