Innate Spellcasting. The zombie lord's spellcasting ability is Wisdom (spell save DC 12). The zombie lord can innately cast the following spells, requiring no material components:

1/day each: animate dead, gentle repose

Legendary Save (1/Day). When the zombie makes a saving throw, it can choose to treat any roll of 9 or lower as a 10.

Stench. Any creature that starts its turn within 10 feet of the zombie lord must succeed on a DC 14 Constitution saving throw or be poisoned until the start of its next turn. On a successful save, the creature is immune to the zombie lord's stench for 24 hours.

Undead Fortitude. If damage reduces the zombie lord to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant or from a critical hit. On a success, the zombie lord drops to 1 hit point instead.

Zombie Mastery. The zombie lord can wrest control of zombies. When a zombie not under the control of the zombie lord starts its turn within 10 feet of the zombie lord, it must succeed on a DC 13 Wisdom saving throw or be subject to the mental commands of the zombie lord, as if the zombie lord had cast the animate dead spell.

Undead Masters. Zombie lords can speak those languages they knew in life and seem to have a telepathic or mystical ability to converse freely with the living dead. Further, they can speak with the dead merely by touching a corpse. Thus, for them at least, dead men do tell many tales.

Zombie Lairs. The zombie lord seeks out places of death as lairs. Often, they will live in old graveyards or on the site of a tremendous battle – anyplace that there are many bodies to animate and feast upon. The mind of a zombie lord tends to focus on death and the creation of more undead. The regions around their lairs are often littered with the decaying bodies, often half eaten, of those who have tried to confront the foul creature. They seldom have grandiose schemes like those often undertaken by vampires or liches, but will frequently plan to take over a small town and turn its entire populace into living corpses.

Undead Nature. A zombie lord doesn't require air, food, drink, or sleep.

Multiattack. The zombie lord makes two slam attacks.

Slam. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 3) bludgeoning damage and 4 (1d8) necrotic damage.

The zombie can take 2 legendary actions, 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. The zombie regains spent legendary actions at the start of its turn.

Command Undead. A zombie under the control of the zombie lord moves up to half its speed and makes an attack.
Slam Attack. The zombie lord makes a slam attack.
Aura of Death (Costs 2 Actions). Each living creature within 15 feet of the zombie lord must make a DC 12 Constitution saving throw. On a failed save, the creature's hit point maximum is reduced by 3 (1d6). If a creature's hit point maximum is reduced to 0 by this effect, the creature dies. This reduction lasts until the creature takes a long rest.