Amorphous. The shadow dragon can move through a space as narrow as 1 inch wide without squeezing.

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

Sunlight Weakness. While in sunlight, the shadow has disadvantage on attack rolls, ability checks, and saving throws.

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

Multiattack. The shadow dragon 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) necrotic damage plus 4 (1d8) acid damage.
Claw. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 13 (2d6 + 6) necrotic damage.
Tail. Melee Weapon Attack: +11 to hit, reach 15 ft., one target. Hit: 15 (2d8 + 6) necrotic damage.
Frightful Presence. Each creature of the shadow dragon's choice that is within 120 feet of the shadow dragon 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 shadow dragon's Frightful Presence for the next 24 hours.
Strength Drain Breath (Recharge 5–6). The dragon exhales necrotic energy in a 60-­‐foot line that is 5 feet wide. Each creature in that line must make a DC 18 Dexterity saving throw, taking 54 (12d8) necrotic damage on a failed save, or half as much damage on a successful one. Additionally the target's Strength score is reduced by 1d4. The target dies if this reduces its Strength to 0. Otherwise, the reduction lasts until the target finishes a short or long rest. If a non-evil humanoid dies from this attack, a new shadow dragon rises from the corpse 1d4 hours later.

The shadow 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 shadow dragon regains spent legendary actions at the start of its turn.
Detect. The shadow dragon makes a Wisdom (Perception) check.
Tail Attack. The shadow dragon makes a tail attack.
Necrotic scream Attack (Costs 2 Actions). The shadow dragon screams in a horrible loud noise. Each creature within 30 feet of the shadow dragon must succeed on a DC 19 Constitution saving throw or take 13 (2d6 + 6) necrotic damage and be stunned.