Branâ Keternâ is Swiss band that plays so-called troll-folk.
The band also features several members of folk-metal band Eluveitie, including Chrigel and Meri.
With traditional Breton, Magyaric, Swedish, medieval Italian and Irish influences, they play various types of traditional music, so it's quite hard to classify them.
They've released one album so far, called Joð.
However, it appears to have sold out, and all the mp3's are downloadable for free at their official website.