Belltoll Revenant

Gloom Lantern. The revenant carries a magical lantern, which sheds dim light in a 30 ft. radius that ignores magical darkness. Creatures other than Undead within the lantern's light cannot regain hit points. Undead creatures within this light, including the revenant, gain resistance to radiant damage.

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

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 have the Stunned condition until the end of its next turn.

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

Spellcasting. The revenant casts one of the following spells, requiring no material components and using Wisdom as its 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

Dolorous Knell (Recharge 5-6). The revenant rings its bell violently, sending waves of despair in a 60 ft. radius. Each creature in the area must make a DC 14 Charisma saving throw, taking 21 (6d6) psychic damage and gaining the Frightened condition on a failure, or half as much damage only on a success. A frightened creature can repeat its 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, that creature is immune to the 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 ft. radius. A non-Undead creature that enters the aura for the first time on its 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 its action to repeat its saving throw, ending the effect on itself on a success. A creature that succeeds on its saving throw is immune to this revenant's aura 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, the spell fails and has no effect. If it is casting a spell of 4th level, or higher, the revenant must make a Wisdom check with a DC equal to 10 + the spell's level. Ona  success, the creature's spell fails and has no effect.