Ancient Shadow Dragon

Living Shadow

While in dim light or darkness, the dragon is immune from sneak attacks.

Shadow Stealth

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

Amphibious

The dragon can breathe air and water.

Ice Walk

The dragon can move across and climb icy surfaces without needing to make an ability check. Additionally, Difficult terrain composed of ice or snow doesn't cost it extra movement.

Lava Walk

The dragon can move across and climb volcanic surfaces without needing to make an ability check. Additionally, Difficult terrain composed of lava or fire doesn't cost it extra movement.

Swamp/Water Walk

The dragon can move across and climb watery surfaces without needing to make an ability check. Additionally, Difficult terrain composed of water doesn't cost it extra movement.

Surprise Attack

If the dragon surprises a creature and hits it with an attack during the first round of combat, the target takes an extra 60 (20D6) damage from the attack.

Legendary Resistance (5/Day)

If the dragon fails a saving throw, it can choose to succeed instead.

Multiattack

The dragon can use its Frightful Presence. It then makes five attacks: one with its bite and two with its claws and one with its tail.

Bite

Melee Weapon Attack: +19 to hit, reach 15 ft., one target. Hit: 25 (4D10 + 10) piercing damage.

Claw

Melee Weapon Attack: +19 to hit, reach 10 ft., one target. Hit: 17 (4D6 + 10) slashing damage.

Tail

Melee Weapon Attack: +19 to hit, reach 20 ft., one target. Hit: 24 (4D8 + 10) bludgeoning damage.

Frightful Presence

Each creature of the dragon's choice that is within 240 feet of the dragon and aware of it must succeed on a DC 30 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.

Breath weapon (Recharge 5-6)

The dragon uses one of the following breath weapons.

Fire Breath

The dragon exhales fire in a 180-foot cone. Each creature in that area must make a DC 30 Dexterity saving throw, taking 88 (18D10) fire damage on a failed save, or half as much damage on a successful one.

Cold Breath

The dragon exhales icy blast in a 180-foot cone. Each creature in that area must make a DC 30 Constitution saving throw, taking 88 (18D10) cold damage on a failed save, or half as much damage on a successful one.

Acid Breath

The dragon exhales acid in a 180-foot cone. Each creature in that area must make a DC 30 Dexterity saving throw, taking 88 (18D10) acid damage on a failed save, or half as much damage on a successful one.

Lightning Breath

The dragon exhales lightning in a 180-foot line that is 10 feet wide. Each creature in that line must make a DC 30 Dexterity saving throw, taking 88 (18D10) lightning damage on a failed save, or half as much damage on a successful one.

Poison Breath

The dragon exhales poisonous gas in a 180-foot cone. Each creature in that area must make a DC 30 Constitution saving throw, taking 88 (18D10) poison damage on a failed save, or half as much damage on a successful one.

Force Breath

The dragon exhales forceful energy in a 180-foot cone. Each creature in that area must make a DC 30 Strength saving throw, taking 88 (18D10) force damage, and is pushed 60 feet away from the dragon on a failed save, or half as much damage on a successful one.

Radiant Breath

The dragon exhales holy energy in a 180-foot cone. Each creature in that area must make a DC 30 Wisdom saving throw, taking 88 (18D10) radiant damage on a failed save, or half as much damage on a successful one.

Psychic Breath

The dragon exhales psionic energy in a 180-foot cone. Each creature in that area must make a DC 30 Intelligence saving throw, taking 88 (18D10) psychic damage, and is confused for a round on a failed save, or half as much damage and is not confused on a successful one.

Thunder Breath

The dragon exhales thunder in a 180-foot line that is 10 feet wide. Each creature in that line must make a DC 30 Dexterity saving throw, taking 88 (18D10) thunder damage on a failed save, or half as much damage on a successful one.

Necrotic Breath

The dragon exhales necrotic energy in a 180-foot line that is 10 feet wide. Each creature in that line must make a DC 30 Wisdom saving throw, taking 88 (18D10) necrotic damage, and is frightened for 1 minute on a failed save, or half as much damage and is not frightened on a successful one.

Paralyzing Breath

The dragon exhales paralyzing gas in a 180-foot cone. Each creature in that area must make a DC 30 Constitution saving throw or be paralyzed for 1 minute. A creature can repeat the saving throw at the end of each of there turns, ending the effect on itself on a success.

Weakening Breath

The dragon exhales gas in a 180-foot cone. Each creature in that area must make a DC 30 Strength saving throw or have disadvantage on Strength-based attack rolls, Strength checks, and Strength saving throws 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.

Slowing Breath

The dragon exhales gas in a 180-foot cone. Each creature in that area must make a DC 30 Constitution saving throw. On a failed save, the creature can't use reactions, its speed is halved, and it can't make more than one attack on its turn. In addition, the creature can use either an action or bonus action on its turn, but not both. These effects last 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.

Repulsion Breath

The dragon exhales repulsion energy in a 180-foot cone. Each creature in that area must make a DC 30 Strength saving throw. On a failed save, the creature is pushed 120 feet away from the dragon.

Change Shape

The dragon magically polymorphs into a humanoid or beast that has a challenge rating no higher that its own, or back into its true for. It reverts to its true form if it dies. Any equipment it is wearing or carrying is absorbed or borne by new for (the dragon's choice).

The Ancient Shadow Dragon can take 5 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. The Ancient Shadow Dragon regains spent legendary actions at the start of its turn.

Detect

The dragon makes a Wisdom (Perception) check.

Tail Attack

The dragon makes a tail attack.

Wing Attack

The dragon beats its wings. Each creature within 30 feet of the dragon must succeed on a DC 30 Dexterity saving throw or take 17 (4D6 + 10) bludgeoning damage and be knocked prone. The dragon can then fly up to half it's flying speed.