You should definitely check out Stormheit if you have not, easily one of the best demos ever released by far. As mentioned, "A Stormride" is an incredible song.
You really can't go wrong Branikald's albums, and all are worth listening to at least once. I really enjoy Av Vinterkald (also known as Winterkald) and Varg Fjerne A Tornet as well.
"Night and Fog" leading into "To a Frigid Luminary of the Night" on Av Vinterkald is brilliant and the likely the type of ambient sound you are mentioning Swizzle.
All of the Blazebirth Hall bands had a very similar sound early on, so there's a good chance you'd enjoy most of them. Raven Dark has already been mentioned by einride... Forest (Rus) is worth checking out as well (the s/t and As a Song in the Harvest of Grief particularly).. you may like Vargleide and Nitberg as well.