Harvester's Doom. The Harvester's Doom is a single weapon that can be broken down into two scythes, which Zaroth wields in each hand. When dual wielding, he gains the benefits of the Dual Wielder feat, allowing him to add his ability modifier to the damage of his off-hand attacks and ignore the "light" property of the Harvester's Doom. When combined, the two scythes form a reach weapon with the two blades extending out from a central handle.

Escape Amulet. When Zaroth is reduced to 0 hit points, the amulet around his neck glows with a bright light and he disappears in a flash of magical energy. He reappears in a safe location, with enough time to heal and regroup before returning to seek revenge on those who defeated him.

Zaroth is immune to the effects of Turn Undead.

Multiattack. When Zaroth wields Harvester's Fang in dual wield mode, he can make two scythe attacks as part of his multiattack. Alternatively, if he combines his two scythes into the double-headed form, he can make one attack with Harvester's Fang and use his action to summon a skeleton to fight alongside him.

Harvester's Doom. Melee Weapon Attack: +9 to hit, reach 5 ft. or 10 ft. (when used as a double-headed scythe), one creature. Hit: 22 (2d10 + 5) slashing damage or 14 (1d8 + 5) slashing damage when used as two separate scythes. 

Summon Wight. Zaroth summons one wight within 60 feet of himself. The wight acts immediately, following Zaroth's orders to the best of its ability. The wight has the same resistances and immunities as Zaroth, and can use its Life Drain ability once per turn. This ability can only be used once per round.

Necrotic Aura (1/Day). Zaroth unleashes a burst of necrotic energy in a 20-foot radius around him. All creatures within the area must make a DC 15 Constitution saving throw, taking 22 (4d10) necrotic damage on a failed save, or half as much on a successful one. Additionally, any undead creatures within the area of effect are healed for the same amount of damage dealt.

Zaroth can take 3 legendary actions per round, choosing from the options below. Only one legendary action option can be used at a time, and only at the end of another creature's turn. Zaroth regains all spent legendary actions at the start of his turn.

Harvester's Doom Attack. Zaroth makes a Harvester's Doom attack.

Intimidating Presence (Costs 2 Actions). Zaroth targets one creature within 30 feet of him that can see him. If the target can see and hear Zaroth, it must succeed on a DC 14 Wisdom saving throw or become frightened for 1 minute. The target 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 Zaroth's Intimidating Presence for the next 24 hours.

Teleport (Costs 2 Actions). Zaroth magically teleports up to 60 feet to an unoccupied space he can see.