And Morr wept.
Throughout the realms his children knew no rest. The sons and daughters of man were ripped from his very hands as he guided them to the afterlife by hostile and wicked gods. Their souls already damaged and torn asunder by the forces of evil while living, and while dead they could not even find sleep beneath the dirt.
His black guard set out into the world and did what they could, but they weren’t prepared for Nagash and his followers. Thousands of the black brothers died protecting his gardens from the unruly dead and their masters. Their souls ripped from their bodies while they still lived by Nagash, and their shells turned against their fellow brothers.
Then it all came to an end.
Morr’s tears flowed black from his skull into the void that remained as countless souls echoed and swam seeking rest and respite, but he could not even grant them a moment. The souls cried out and begged for him, but he was powerless against the dark gods.
Shylla looked upon her father’s face and knew what must be done, she set about gathering the souls, but for every one she saved a thousand black sons were devoured by Chaos. She took what she could and pleaded with Sigmar to help them.
Sigmar looked upon the maiden’s face and saw her sorrow and felt pity, so he took the souls by the handful and upon his anvil he built them anew against thunder and smoke. What stood up from his anvil weren’t men, they were vengeful sons who sought retribution for lost brothers. Black tears wept from their emotionless masks in solidarity with their father.
The Sons of Morr are an Eternal Stormhost consisting of the lost souls of Black Priests of Morr. In the End Times they fell combating the hordes of undead and wicked humans that turned to the dark arts. They defended the peace and rest of lost souls and were determined to grant every man, woman, and child a proper burial so their spirits would know sleep.
They are vengeful husks now, knowing their mission can never be finished and knowing what was stripped from them. They are blessed with armored shells by Sigmar and their essence touched by Morr himself. They are his divine will set about in the realm of Shyish, seeking to undo the madness of Nagash and his followers, as well as anyone who dare interrupt the sleep of the departed.