Innate Spellcasting. The dragon's innate spellcasting ability is Charisma (spell save DC 14). It can innately cast the following spells:

1/Day each: create or destroy water, fog cloud

 Living Shadow. While in dim light or darkness, the dragon has resistance to damage that isn’t force, psychic, or radiant.

Shadow Stealth. While in dim light or darkness, the dragon can take the Hide action as a bonus action.

Sunlight Sensitivity. While in sunlight, the dragon has disadvantage on attack rolls, as well as on Wisdom (Perception) checks that rely on sight.

Multiattack. The dragon makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 15 (2d10 + 4) piercing damage.

Claw. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) slashing damage.

Breath Weapons (Recharge 5–6). The dragon uses one of the following breath weapons.

Fire Breath. The dragon exhales shadowy fire in a 40-foot line that is 5 feet wide. Each creature in that line must make a DC 15 Dexterity saving throw, taking 42 (12d6) necrotic damage on a failed save, or half as much damage on a successful one.  A humanoid reduced to 0 hit points by this damage dies, and an undead shadow rises from its corpse and acts immediately after the dragon in the initiative count. The shadow is under the dragon’s control.

Nightmare Breath. The dragon exhales nightmare gas in a 30-foot cone. Each creature in that area must succeed on a DC 14 Wisdom saving throw or be stunned until the end of its next turn and frightened for 1 minute. A creature that succeeds on the saving throw is frightened until the end of its next turn but suffers not additional effect. This effect ends for a creature if the creature takes damage.