Adult Deep Shadow Dragon

Armor Class 17 (Natural Armor)

Hit Points 147 (14d12 + 56)

Speed 40 ft., swim 40 ft., burrow 30 ft., fly 80 ft.

STR

20 (+5)

DEX

14 (+2)

CON

18 (+4)

INT

16 (+3)

WIS

16 (+3)

CHA

18 (+4)

Saving Throws DEX +7, CON +9, WIS +8, CHA +9

Skills +8, +14, +17

Damage Resistances Necrotic, Poison, Psychic

Condition Immunities , ,

Senses 60 ft., 150 ft., Passive Perception 17

Languages Common, Deep Speech, Draconic

Challenge 15 (13,000 XP)

Proficiency Bonus +5

Traits

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

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

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

Actions

Multiattack. The dragon makes one Bite attack and two Claw attacks.

Bite. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 16 (2d10 + 5) piercing damage plus 5 (1d10) necrotic damage.

Claw. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 8 (1d6 + 5) slashing damage.

Tail. Melee Weapon Attack: +9 to hit, reach 15 ft., one target. Hit: 9 (1d8 + 5) bludgeoning damage. If the target is a creature, it must succeed on a DC 17 Strength saving throw or be knocked .

Change Shape. The dragon magically transforms into any creature that is Medium or Small, while retaining its game statistics (other than its size). This transformation ends if the dragon is reduced to 0 hit points or uses its action to end it.

Nightmare Breath (Recharge 5–6). The dragon exhales a cloud of spores in a 60-foot cone. Each creature in that area must make a DC 16 Wisdom saving throw. On a failed save, the creature takes 33 (6d10) necrotic damage, and it is of the dragon for 1 minute. On a successful save, the creature takes half as much damage with no additional effects. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

A humanoid reduced to 0 hit points by this damage dies, and an undead rises from its corpse and acts immediately after the dragon in the initiative count. The is under the dragon's control.

Bonus Actions

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

Legendary Actions

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

Commanding Spores. The dragon releases spores around a creature within 30 feet of it that it can see. The target must succeed on a DC 16 Wisdom saving throw or use its reaction to make a melee weapon attack against a random creature within reach. If no creatures are within reach, or the target can't take a reaction, it takes 5 (1d10) psychic damage.
Tail. The dragon makes one Tail attack.
Spore Salvo (Costs 2 Actions). The dragon releases poisonous spores around a creature within 30 feet of it that it can see. The target must succeed on a DC 16 Constitution saving throw or take 17 (5d6) poison damage and become poisoned for 1 minute. The poisoned creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Mythic Actions

Lair and Lair Actions

Lair Actions

On initiative count 20 (losing initiative ties), the dragon can take one of the following lair actions; the dragon can't take the same lair action two rounds in a row:

Deep Torpor. The dragon casts the slow spell, requiring no spell components and using Charisma as the spellcasting ability (spell save DC 16). The spell ends early if the dragon uses this lair action again or if the dragon dies.
Mossy Sludge. The dragon conjures sludge-like moss that briefly covers surfaces in the lair. The ceiling, floor, and walls of the lair become difficult terrain until initiative count 20 on the next round.
Toxic Spores. The dragon fills a 20-foot cube it can see within 120 feet of itself with toxic spores. Each creature in that area must succeed on a DC 15 Constitution saving throw or take 14 (4d6) poison damage and be poisoned until the end of its next turn.