Amphibious. The dragon zombie can breathe air and water.

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

Undead Fortitude. If damage reduces the dragon zombie 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 zombie drops to 1 hit point instead.

Multiattack. The dragon zombie can use its Frightful Presence. It then makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit: 17 (2d10 + 6) piercing damage plus 7 (2d6) 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.

Frightful Presence. Each creature of the dragon zombie's choice that is within 120 feet of the dragon zombie and aware of it must succeed on a DC 16 Wisdom saving throw or become frightened for 1 minute. 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 Frightful Presence for the next 24 hours.

Poison Breath (Recharge 5–6). The dragon zombie exhales poisonous gas in a 60-foot cone. Each creature in that area must make a DC 18 Constitution saving throw, taking 56 (16d6) poison damage on a failed save, or half as much damage on a successful one.

The dragon zombie 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 zombie regains spent legendary actions at the start of its turn.

Detect. The dragon zombie makes a Wisdom (Perception) check.

Tail Attack. The dragon zombie makes a tail attack.

Wing Attack (Costs 2 Actions). The dragon zombie beats its wings. Each creature within 10 feet of the dragon zombie must succeed on a DC 19 Dexterity saving throw or take 13 (2d6 + 6) bludgeoning damage and be knocked prone. The dragon zombie can then fly up to half its flying speed.