I've always found Mortem to be pretty fucking boring. However, I only speak from knowledge of Decomposed By Possession. I'd be open to hearing their earlier material.
I think my main contribution this evening to this thread will have to be Vile - Depopulate. Beautifully intricate crushing new school Death Metal. Almost never hear it mentioned. This album succeeds where their first album failed.
As always, thanks Apostate for gracing us with your unparalelled metal knowledge and highly refined taste.
Updated list:
Mortal Decay - Sickening Erotic Fanaticism, Forensic
Throne of Ahaz - Nifelheim
Eucharist - A Velvet Creation
Monstrosity - Millennium
Adramelech
Vile - Depopulate
and... tell me what you think about these:
Alghazanth - Thy Aeons Envenomed Sanity
Birkenau - In The Falling Snow
Obtained Enslavement - Centuries Of Sorrow, Witchcraft, Soulblight
Varathron - Walpurgisnacht
Valar - Magic And Wyrmfire
Weltmacht - And To Every Beast Its Prey
Blut Aus Nord - Mystical Beast Of Rebellion, The Work Which Transforms God
Ohtar - Woodland Desolation
Belketre - Ambre Zuetki Vuordravartre
Arcturus - Aspera Hiems Symfonia
Axis Of Advance - Strike
Brutal Truth - Need To Control
Dub Buk - Misyac Pomsty
Finntroll - Midnattens Widunder
Forest - Like A Blaze Above The Ashes
just some random stuff off the top of my head.