Avaritia

Innate Corruption.
Any creature that starts its turn within 10 ft. of Avaritia must succeed on a DC 15 Charisma saving throw or gain one level of Despair. Despair levels stack up to three. Despair lasts until the end of a creature’s next long rest or once Avaritia is reduced to 0 hit points.
• Level 1 – Disadvantage on the next attack roll.
• Level 2 – Speed is halved and the creature can’t take reactions.
• Level 3 – The creature can’t regain hit points.

Aura of Isolation.
All creatures within 30 ft. of Avaritia are considered alone. They can’t benefit from allies’ reactions, auras, or Help actions. Magical communication (e.g. telepathy, sending, etc.) within this aura fails.

Multiattack. Avaritia makes two attacks with Withering Barbs and may use Devour Hope if available. 

Withering Barbs. Melee Attack Roll: +7, reach 10 ft. Hit: 15 (2d10 + 4) necrotic damage.
The target must succeed on a DC 15 Constitution saving throw, or its hit point maximum is reduced by the necrotic damage taken. This effect lasts until the target finishes a long rest.

Devour Hope (Recharge 5–6).
Avaritia targets one creature it can see within 60 ft. The target must make a DC 15 Charisma saving throw, taking 27(6d8) psychic damage on a failed save, or half as much on a success.
On a failure, the target also gains one level of Despair.

Manifest Guilt (1/Day). Avaritia projects haunting visions of failure and regret. Each creature within 30 ft. must succeed on a DC 15 Wisdom saving throw or become paralyzed for 1 minute, overcome with grief. A creature may repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Avaritia can take 3 legendary actions, choosing from the options below. Only one legendary action may be used at a time and only at the end of another creature’s turn. Avaritia regains spent legendary actions at the start of its turn.

Creeping Curse. Avaritia targets a creature it can see within 30 ft. The target must make a DC 15 Charisma saving throw, or become cursed for 1 minute. While cursed, the creature has disadvantage on all Charisma checks and saving throws.

Twist Emotion. Avaritia targets one creature within 30 ft. The target must make a DC 15 Wisdom saving throw, or become hostile toward one of its allies until the end of its next turn.

Slither. Avaritia moves up to its speed without provoking opportunity attacks.