It is impossible to categorize Moon Lay Hidden's music. The basic structure of their songs is generally medieval -- but if you are imagining singsong melodies, pretty dulcimer, and the ethereal vocals of Lisa Gerrard played at a Ren Fair or during the epiphanic scene in a fantasy movie, then you're already far wrong.
Though TMLHBAC does have its pretty moments, their rhythm is provided by snare drums, jackboots, and the barked orders of military generals, sampled off of scratchy LP's from the 1940's and washed in thudding electronics. Think of what would happen if Dead Can Dance found itself on a smoking battlefield created by Laibach, and you'll be almost there.
TMLHBAC's vocals are provided by howling demons a woman named Alzbeth who, while not having quite the vocal range of Diamanda Galas, certainly shares her passion and possession, and who, like Diamanda, sings in multiple languages. Other sounds -- industrial, military, and medieval -- are provided by the band's other member, Albin Julius.
Perhaps the best way of describing TMLHBAC is simply by saying that they are a World Serpent band: like all other World Serpent bands, they are dark, experimental, and obsessed with occult themes. However, they have always been somewhat tangential to the main axis of World Serpent artists. They were based in Austria, so they never really got involved with the core of English musicians in Current 93, Nurse With Wound, or Sol Invictus. They maintained ties with their own record label, which was called Arthur's Round Table -- and, unlike the case with Durtro or United Dairies, that label was never subsumed under World Serpent's aegis. Furthermore, they seemed to keep a much lower profile than other WSD bands did. They did not like being interviewed or having their pictures published; they (infuriatingly!) did not give titles to any of their songs, making the music very hard to review or cite; and they very rarely performed live.
Albin Julius eventually went on to work with Death In June, but only after that band had left the World Serpent label, and only when TMLHBAC was on the verge of breakup itself. After Moon Lay Hidden disbanded in 1998, Albin grew closer to Douglas P., and continues to appear on DIJ's albums from time to time. At the same time he is active working on his own solo project, Der Blutharsch. Alzbeth has promised to release her own solo recordings for some years now, but so far as I am aware, none of them have seen the light of day.
Every World Serpent band has its obsessions, and for Moon Lay Hidden, they all have to do with the oppression of the peasants by the medieval Catholic Church, the hypocrisy of priests and kings, and the suffering of soldiers, slaves, and children. In interviews, Alzbeth can get downright preachy about this stuff, but the fearsomeness of her vocal delivery saves her records from the sort of monotonous didacticism that makes the music of so many angry pagan bands completely unlistenable.
Discography:
Even at its most melodic, TMLHBAC is menacing and aggressive, and the prettiest songs are usually the ones with the most violent lyrics. That said, Amara Tanta Tyri could probably pass for a Dead Can Dance album in dim light, and since it is the most "accessible" of the lot, it is the one I usually recommend to people just starting out. My personal favourite is probably Were You Of Silver, though The Smell of Blood is a close second.
Incidentally, I spent many years believing that Moon Lay Hidden was a "minor" World Serpent artist and that I was the only person who listened to them. But then I read an e-mail where Alison Webster of World Serpent mentioned in passing that TMLHBAC was in fact one of their best-selling artists. Despite (or perhaps because of) their mysteriousness, they managed to grow popular, at least in Europe, through word of mouth.