Belltoll Revenant

Gloom Lantern. The revenant's lantern sheds dim light in a 30- foot radius that pierces  magical darkness. Non-Undead creatures in the lantern’s light cannot regain hit points. Undead in the light, including the Belltoll Revenant, gain resistance to radiant damage.

Magic Resistance. The revenant has advantage on saving throws against spells and other magical effects.

Spellcasting. The revenant casts one of the following spells, requiring no material components and using Wisdom as the spellcasting ability (spell save DC 14):
At will: chill touch, minor illusion
2/day each: darkness, false life, silence
1/day each: black tentacles, blight

Multiattack. The revenant makes two Doom Bell attacks and one Chains of the Damned attack.

Doom Bell. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 12 (2d8 + 3) bludgeoning damage plus 7 (2d6) psychic damage. If the target is a creature, it must succeed on a DC 14 Wisdom saving throw or be stunned until the end of its next turn.

Chains of the Damned. Melee Spell Attack: +6 to hit, range 30 ft., one creature. Hit: The target is grappled (escape DC 16). While grappled in this way, the creature is restrained, and it takes 10 (3d6) necrotic damage at the start of each of its turns.

Dolorous Knell (Recharge 5-6). The revenant rings its bell violently, sending waves of despair in a 60-foot radius. Each creature in the area must make a DC 14 Charisma saving throw. On a failure, a creature takes 21 (6d6) psychic damage and is frightened for 1 minute. On a success, a creature takes half as much damage and isn't frightened. A frightened creature can repeat the saving throw at the end of each of its turns, ending
the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the Belltoll Revenant's Dolorous Knell for the next 24 hours.

Aura of Sorrow. The revenant activates or dispels a shadowy aura of dark energy. While active, the revenant radiates an aura of sorrow in a 30-foot radius. A non-Undead creature that enters the aura for the first time on a turn or starts its turn there must succeed on a DC 14 Wisdom saving throw or be afflicted with a soul-chilling melancholy. A melancholic creature has disadvantage on attack rolls and ability checks. The creature can use an action to repeat the saving throw, ending the effect on itself on a success. A creature that succeeds on the saving throw is immune to the revenant's Aura of Sorrow for the next 24 hours.

Counterspell (1/Day). The revenant attempts to interrupt a creature in the process of casting a spell. If the creature is casting a spell of 3rd level or lower, its spell fails and has no effect. If it is casting a spell of 4th level or higher, the Belltoll Revenant must make a Wisdom check with a DC equal to 10 + the spell’s level. On a success, the creature’s spell fails and has no effect.