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

Undead Fortitude. If damage reduces the dragon 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 dragon drops to 10 hit points instead.

Multiattack. The dragon can use its Sickening Presence. It then makes three attacks: one with its salivating maw and two with its claws.

Salivating Maw. Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit: 17 (2d10 + 6) piercing damage, plus 5 (2d4) poison damage.

Claw. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 13 (2d6 + 6) slashing damage.

Tail. Melee Weapon Attack: +11 to hit, reach 15 ft., one target. Hit: 15 (2d8 + 6) bludgeoning damage.

Sickening Presence. Each creature of the dragon's choice that is within 120 feet of the dragon and aware of it must succeed on a DC 20 Constitution saving throw or become poisoned for 1 minute, while poisoned in this way a creature takes 5 (2d4) poison damage at the start of each of their turns, a humanoid reduced to 0 hit points by this damage dies, and rises as a zombie and acts immediately after the dragon in the initiative count. The zombie is under the dragon’s control. . A creature 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 the dragon's Intoxicating Presence for the next 24 hours.

Plague Breath (Recharge 5–6). The dragon coughs out a toxic miasma in an 60-foot cone. Each creature in the cone must make a DC 20 Constitution saving throw, taking 63 (14d8) poison damage on a failed save, or half as much damage on a successful one the creature has disadvantage on the saving throw if they are poisoned. A humanoid reduced to 0 hit points by this damage dies, and rises as a zombie and acts immediately after the dragon in the initiative count. The zombie is under the dragon’s control.

Undead Hive Mind's Vengance. When a creature within 150 feet of the dragon deals damage to the dragon, the dragon can use its reaction to cause one zombie under the dragon's control within 20 feet of the creature to move up to its speed and make a melee attack against the creature.

The dragon can take 3 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 dragon regains spent legendary actions at the start of its turn.

Tail Attack. The dragon makes a tail attack.

Undead Regeneration (Costs 2 Actions). The dragon regains 13 (2d12) hit points.

New Friends! (Costs 3 Actions). The dragon belches out 2 (1d4) zombies, the zombies appear in a space within 5 feet of the dragon, they are prone and take their turn at the end of the dragon's next turn. The zombies are under the dragon's control.