Incorporeal Movement. The abandoned zealot can move through other creatures and objects as if they were difficult terrain. It takes 5 (1d10) force damage if it ends it's turn inside an object.

Sense Apostate. The banshee can sense the presence and direction of false priests or clergy up to 1 mile away.

Turn Resistance. The abandoned zealot has advantage on saving throws against any effect that turn undead.

Hand of Despair. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 25 (4d10 + 3) psychic damage. 

Rend Faith (Recharge 5-6). The abandoned zealot reaches into the mind of any number of creatures of its choice within 30 feet that it can see and attempts to shred all sense of belief and hope. Each affected creature must make a DC 13 Wisdom saving throw or take 14 (4d6) psychic damage and become frightened until the end of their next turn, or half as much damage and are not frightened on a success. Creatures who have the ability to cast divine spells or have strong belief in a higher power that fail their saving throw take an additional 7 (2d6) psychic damage and are unable to cast any spells until their end of their next turn, or take half as much damage and are able to cast spells as normal.

Elegy of the Faithless. When a spell that restores hit points or from a divine source is cast within 60 feet of the abandoned zealot, it howls an elegy of regret and attempts to interrupt the spell as if had cast counterspell at 3rd level.