Yes, they are from Sweden. Therion is the brainchild of Christofer Johnsson, who started the band out as a brutal death metal band under the name Blitzkrieg in the very late 80's, not realizing there already existed a band of that name. So when they started producing material, they changed their name to Therion - partly as an ode to his favorite band of that era, Celtic Frost.
Over the years, Therion has evolved to become less of a death metal band and more of a symphonic heavy metal band. But in a sea of symphonic metal bands that exist these days, they truly stand out from the crowd. Their music delivers an energy I have not felt from other 'epic' metal bands.
It's funny how Bryant has compared Tad Morose to Accept for sheer energy and feeling. I feel the exact same way about Therion - they have this raw energy that you could feel from a band such as Accept in the late 80's, yet they temper it with classical arrangements, soaring choirs, and wonderful operatic soloists - male and female.
As far as which album to start with, Urban, I'd have to recommend
Vovin. It seems to have a calm energy about it, but still maintains the pure power. Beyond that, go back one album to
Theli, which is where I discovered them. Following Vovin in their library is
Deggial, which was their first effort with a full orchestra. For a personal favorite, I think I prefer their last studio album,
Secret of the Runes - an album which discusses the Norse Mythos through song. Beautiful.
Therion is a band that somehow gets better and better with each release. And their newest release, over 3 years in the making, is a double cd called Lemuria/Sirius B - an amazingly ambitious production that blends Scandinavian heavy metal with elements taken from Nordic folk, death metal, classical music & opera; all performed by over 170 musicians!!! You can read a good review and hear some samples at this site:
http://www.metalcovenant.com/pages/index.htm
I'm amazed that Tad Morose hasn't toured with them before, other than a stint at that festival you mentioned. I think that would be a great combination. Because even though I make it sound like Therion is some gigantic production number, really it isn't. If you could ever see their videos, you'd understand. It's just a few musicians on stage presenting some wonderful heavy metal music.
Anyway, thanks for the response Urban. I look forward to hearing your opinion about
Therion. And you may find out all about the band, as well as sample more music here:
http://www.megatherion.com/
Have a great day!
~Hoyt.