Amphibious. The priest can breathe air and water.
Innate Spellcasting. The priest's spellcasting ability is Wisdom (spell save DC 12, +4 to hit with spell attacks). It can innately cast the following spells, requiring no material components:
At will: command, cause fear.
3/day each: darkness, bestow curse, shadow blink, shadow of Moil.
1/day each: Evard's black tentacles, vampiric touch
Necrotic Touch. Melee Spell Attack: +4 to hit, reach 5 ft., one creature. Hit: 27 (5d10) necrotic damage.
Voice of the Council (Recharges after a Short or Long Rest).
The council speaks through the priest with a thunderous voice audible within 300 feet. Creatures of the priest's choice that can hear the councils words (which are spoken in Primordial) must succeed on a DC 13 Charisma saving throw or be frightened for 1 minute. A frightened target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.