The priest is a 5th-level spellcaster. Its spellcasting ability is Charisma (spell save DC 13, +5 to hit with spell attacks). It knows the following sorcerer spells:
Cantrips (at will): acid splash, blade ward, light, mending, Mold Earth*
1st level (4 slots):
Xanathar's Guide to Everything
1-level Evocation
You cause a tremor in the ground within range. Each creature other than you in that area must make a Dexterity saving throw. On a failed save, a creature takes 1d6 bludgeoning damage and is knocked prone. If the ground in that area is loose earth or stone, it becomes difficult terrain until cleared, with each 5-foot diameter portion requiring at least 1 minute to clear by hand.
At higher levels: When you cast this spell using a spell slot of 2nd level or higher, the damage increases by 1d6 for each spell slot above 1st.
Unyielding. When the priest is subjected to an effect that would move it, knock it prone, or both, it can use its reaction to be neither moved nor knocked prone.
Glaive. Melee Weapon Attack: +4 to hit, reach 10 ft., one target. Hit: 7 (1d10 + 2) slashing damage
The priests of the Black Earth are the drivers and organizers of Ogremoch’s cult. They are the true believers, seeing Ogremoch as a divine force, and they have developed a twisted dogma to explain how the evil of elemental earth is destined to remake the world and rule over all. The Black Earth priests form a cabal of leaders whose fanaticism and magical power serve as the backbone of the cult. Individuals of unusual power hold higher rank in the cult, but the priests provide the cult leader with his or her authority over the rest of Ogremoch’s followers.