Apolion's Genocide were a Columbian black metal band who, despite being around for 7 years (or more), only released 3 demos. This is the only one I've heard, but I've been told that the other two do not compare, but that also isn't saying too much considering how incredible this demo is.
The music on Olupicsid Nu A Anedro Sathanas is very atmospheric and haunting black metal, somewhat similar to the first two Samael albums. But like I said, only somewhat. This demo really stands on its own in terms of uniqueness. For the most part, this demo is pretty doom-paced but of course it is completely and undeniably black metal, with it the atmosphere created by the cold and chilling guitars, creepy bass, double tracked vocals (one a higher black metal rasp and another a death growl), excellent use of organ synths and crawling drums (although that is not an uncommon quality found in doom metal). It may not sound like anything mind-blowing, which is really why you need to hear this for yourself.
This demo will surely possess you as it did to me, and that is a promise. Download, download, download.