For Amendez: Drowning Pool - Duet
For Yammael (My lovely Warlock): Machines of Loving Grace - Golgotha Tenement Blues
For Azaviel (My Priest): Porcupine Tree - Halo
For Corpue (My Warrior): Children of Bodom - In Your Face
Hate it or love it, but you cannot deny: this music fits perfectly to Death Knights. I saw them live last year and the whole atmosphere was so dark and evil <3
For some reason I see certain type of Classical to be a more of a fit.. Try Epica.