Blightborne Revenant

Undead Restoration. If the revenant is destroyed, it returns to life with all its hit points 24 hours later, provided there are corpses in the same room.

Corpse Conduit. When a zombie merges with the revenant, its current hit points are transferred to the revenant, and the revenant regains that many hit points. If this healing would cause the revenant to exceed its hit point maximum, the excess is gained as temporary hit points instead. These temporary hit points can stack and have no duration limit.

Corpse Colossus. The revenant is a Huge creature. If the revenant’s current hit points (including temporary hit points) exceed 440 (twice its hit point maximum), it grows to Gargantuan size. While Gargantuan, it has advantage on Strength checks and Strength saving throws. This transformation persists until its current hit points fall below 330 (1.5 times its hit point maximum).

Legendary Resistance (3/Day). If the revenant fails a saving throw, it can choose to succeed instead.

Multiattack. The revenant makes two Suffocate attacks, or one Haunting Glare attack.

Suffocate. Melee Attack Roll: +12, reach 10 ft. Hit: 15 (1d12 + 7) Bludgeoning damage plus 14 (4d6) Necrotic damage. If the target is a Large or smaller creature, it has the Grappled condition (escape DC 17). Until the grapple ends, the target is suffocating. The revenant can have up to two targets Grappled in this way at a time.

Haunting Glare (Recharge 5–6). Wisdom Saving Throw: DC 17, each creature in a 30-foot Emanation originating from the revenant. Failure: The target has the Paralyzed condition and repeats the save at the end of each of its turns, ending the effect on itself on a success. After 1 minute, it succeeds automatically.

Aura of Withering. The revenant invokes the lingering curse of its Haunting Glare. Each creature currently paralyzed by Haunting Glare within 30 feet of the revenant has its hit point maximum reduced by 5. This reduction lasts until the affected creature finishes a long rest or the revenant is destroyed.