The genre is "funeral doom." This means, at a minimum, you can expect "very low" and "very slow." In the case of Mirror Reaper, this means lots of very deep guitar chords or drones, hollow chthonic growls, and lurching, resonant percussion.
That's not all, though. The lighter solo interludes are melancholy and beautiful, echoing clean vocals (almost Gregorianic) form solemn choirs, and guest vocalist Erik Moggridge transforms the second half of the album into something heartbreakingly special.
I'm not even really into "funeral doom," but I love this.
Mirror Reaper is for listening to when exploring cyclopean ancient ruins, dreaming of depths and shadow, or contemplating the inevitability of the erasure of all that you hold dear.
Give it a listen. It's not distracting from whatever you happen to be doing for a quiet hour.
(Yeah, probably gonna write up a "mirror reaper" and/or "bell witch" for my tabletop game at some point, haha. Not today, though; I'm tired, and packing for a move.)