Judgement of the Dead and The Black Mass (you've heard both) are from "Volume 1" which is old school satanic doom, as you can tell.
The other release, Lords of Hypocrisy, which is equally old stuff re-recorded, seems to be less heavy doom-like and more 70's proggy doom with hints of psychadelia and Floyd.
Both releases are essential. IoftheStorm seems to prefer LoH, and based on his general tastes that's no surprise, but so far I think I prefer the raw and heavy nature of Volume 1. Again though, both are worth it.