Mordiggian is old and omnipotent as death. He was worshipped in former continents, before the lifting of Zothique from out the sea. Through him, we are saved from corruption and the worm. Even as the people of other places devote their dead to the consuming flame, so we of Zul-Bha-Sair deliver ours to the god. Awful is the fane, a place of terror and obscure shadow untrod by the sun, into which the dead are borne by his priests and are laid on a vast table of stone to await his coming from the nether vault in which he dwells. No living men, other than the priests, have ever beheld him; and the faces of the priests are hidden behind masks of silver, and even their hands are shrouded, that men may not gaze on them that have seen Mordiggian.-The Charnel God by Clark Ashton Smith
My own take on the Charnel God for my campaign world.
Mordiggian’s temples are scattered throughout Zoong. Some are tolerated like in Ularax whiles are hidden in shadow. Ghouls and other eaters of the dead view Mordiggian as the God of the Eternal Harvest. More civilized (and living folks) barely tolerate Mordiggian as a God of Funerary rites. He is not the God of the Dead nor does have anything to do with pass of the soul or spirit into the Afterlife but what happens to the mortal remains. In these areas, the Cult does have a mortal high priest who acts as the public face of the Cult.
Clerics of Mordiggian have a special rapport with low level undead. With a (D)estroy result on a Turn Undead attempt, the cleric may opt to change the attitude of undead to “Friendly”. How the GM determines what a “Friendly” reaction from a horde of zombies, well, that’s up to the GM.