The most cunning and treacherous of true dragons turned to the shadowfell , green dragons use misdirection and trickery to get the upper hand against their enemies , but ever since his transformation a strange melancholy accompnies his action. A green dragon is recognized by the crest that begins near its eyes and continues down its spine, reaching full height just behind the skull now creating a gazeous grey smoke.

Forest-loving green dragons usually compete for territory with black dragons in marshy woods and with white dragons in subarctic taiga. However, a forest controlled by a green dragon is easy to spot. A perpetual fog hangs in the air in a legendary green dragon’s wood, carrying an acrid whiff of the creature’s poison breath. 

After years passed in the shadowfell the lair he created is different from a green dragon's lair . The moss-covered trees are now sick and falling onto each other creating something like a maze into the heart of the dark and cursed forest. The light that reaches the forest floor carries an umbral grey cast, and every sound seems distant and eery. The fog that engulf the area as now  dark grey teint to it and have only a left-over smell of acrid poison. 

Near an entrance to the Sadowfell and preferably in the heart of a forest the dragon as corrupted, a shadow dragon chooses a cave in a sheer cliff or hillside for its lair, preferring an entrance hidden from prying eyes. Some seek out cave mouths concealed behind dark wood swamps trees.

Lair Actions

On initiative count 20 (losing initiative ties), the dragon takes a lair action to cause one of the following effects; the dragon can’t use the same effect two rounds in a row:

• Pitch Black: The darkness of the Shadowfell condenses into a 45ft cube from a point within the lair that the dragon can see within 120 feet. Nothing can See, Hear, or Otherwise Perceive through or In this Darkness . The darkness wilt away when the dragon uses this lair action again or when the dragon dies.
• Banish Light. Any nonmagical source of illumination within a 60-foot-radius sphere centered on the dragon is snuffed out, and any spell that creates light within that same area is dispelled.
• Wall of Shadow: A wall of Condensed shadow spikes thorns springs into existence within 120 feet of the dragon. The wall is up to 50 feet long, 15 feet high, and 5 feet thick, and it blocks line of sight. When the wall appears, each creature in its area must make a DC 15 Dexterity saving throw. A creature that fails the save takes 18 (4d8) piercing damage and is pushed 5 feet out of the wall’s space, appearing on whichever side of the wall it wants. A creature can move through the wall, albeit slowly and painfully. For every 1 foot a creature travels through the wall, it must spend 5 feet instead. Furthermore, a creature in the wall’s space must make a DC 15 Dexterity saving throw once each round it’s in contact with the wall, taking 18 (4d8) piercing damage on a failed save, or half as much damage on a successful one. Each 10-foot section of wall has AC 5, 15 hit points, vulnerability to radiant damage, resistance to bludgeoning and piercing damage, and immunity to necrotic damage. The wall sinks back into the ground when the dragon uses this lair action again or when the dragon dies.

Regional Effects

The region containing a legendary shadow dragon’s lair is warped by the dragon’s magic, which creates one or more of the following effects:

• Shadowy tendrils form labyrinthine passages within 1 mile of the dragon’s lair. The tendrils act as 10-foot-high, 10-foot-thick walls that block line of sight. Creatures can move through the tendrils, with every 1 foot a creature moves costing it 5 feet of movement. A creature in the tendrils must make a DC 15 Dexterity saving throw once each round it’s in contact with the thickets or take 3 (1d6) piercing damage from thorns.
  Each 10-foot-cube of tendrils has AC 5, 25 hit points, resistance to bludgeoning and piercing damage, vulnerability to radiant damage, and immunity to psychic and necrotic damage.
• Within 1 mile of its lair, the dragon leaves no physical evidence of its passage unless it wishes to. Tracking it there is impossible except by magical means, and even so. In addition, it ignores impediments from darkness and damage from necrotic sources in this area that are neither magical nor creatures, including the tendrils described above. The shadow tendrils remove themselves from the dragon’s path.
• Shadow and Shades within 1 mile of the dragon’s lair serve as the dragon’s eyes and ears. animals and other large game are strangely absent, hinting at the presence of an unnaturally hungry predator.
• Dying Light. Light is diminished within 6 miles of the dragon’s lair, litghly obscuring the land in gloomy shadows.

• Gloomy Portals. Some caves, caverns, pits, and other places of deep gloom within 1 mile of the dragon’s lair form portals to the Shadowfell, allowing creatures from that plane to dwell nearby.

If the dragon dies, the Shadows and Shades lose their supernatural link to it. The tendrils remain, but within 1d10 days, they become mundane and normal difficult terrain, losing their thorns.