I'm surprised this collaboration didn't happen sooner. Altar finds Boris going back to their doom roots circa Absolutego while as the guys from Sunn O))) crank up a few bpms. The album definitely sounds like the two are in perfect symbiosis even though there are many unexpected surprises in store. Some tracks could be qualified as dark ambient (N.L.T.), others are in the expected doom vein (Etna & Blood Swamp), but some fall squarely outside of both of these artists' registry. The gloomy, western-tinged The Sinking Belle (Blue Sheep) is a good example, with it's soft female vocals and Flood-era guitar work. Fried Eagle Mind sounds like one of those freaky "space whisper" tracks by Gong and even Akuma No Kuma sounds as if Trans Am have taken over the studio. This limited edition comes with a second CD including Her Lips Were Wet From Venom, a doom masterpiece with Dylan Carlson.