The soul of the Undead is the most important, so no matter what form the body takes, the Mourning Soul cannot become the Black Crystal Soul.
"Soul Strength is the most important, but this damned place has too little breath of death," the Monarch said with distress.
Indeed, it is too little. It cannot compare to inside the death zone of the Star Burst Plane, nor to the Resting Abyss. The breath of death in Chaotic Burial Mound is considered dense, yet on his first day, the Monarch nearly cleared out all the lingering Breath of Death.
If it were a world like the Star Burst Plane, the Monarch would have gathered all the deceased souls long ago, found a place with poor airflow, sparse moisture, and dry conditions to lie the corpses, amassing a large number of corpses, which would have generated the breath of death much faster.
