Cruel Entertainment. When a creature The Zealot of Cithrel can see within 60 feet of him is reduced to 0 hit points, the zealot gains 25 temporary hit points.

Legendary Resistance (3/Day). If The Zealot of Cithrel fails a saving throw, he can choose to succeed instead.

Multiattack. The Zealot of Cithrel gets two Chain's of Cithrel attacks, and it uses 

Chains of Cithrel. Melee Weapon Attack: +6 to hit, reach 15 ft., one target. Hit: 8 (1d4 + 6) slashing damage plus 10 (3d6) psychic damage.

Hellfire. Green flame explodes in a 10-foot-radius sphere centered on a point within 120 feet of the warlock. Each creature in that area must make a DC 15 Dexterity saving throw, taking 16 (3d10) fire damage and 11 (2d10) necrotic damage on a failed save, or half as much damage on a successful one.

Spellcasting. The zealot casts one of the following spells, using Wisdom as the spellcasting ability (spell save DC 15):

At will: light, spare the dying, thaumaturgy

1/day each: banishment, command, dispel magic, flame strike, guardian of faith, hold person, lesser restoration, revivify

Healing Light (2/Day). The Zealot of Cithrel or one creature of its choice within 60 feet of it regains 12 (2d8 + 3) hit points.

Fiendish Rebuke (3/Day). In response to being damaged by a visible creature within 60 feet of it, the Zealot of Cithrel forces that creature to make a DC 15 Constitution saving throw, taking 22 (4d10) necrotic damage on a failed save, or half as much damage on a successful one.