Shadow dragons are true dragons that were either born in the Shadowfell or transformed by years spent within its dismal confines. Some shadow dragons embrace the Shadowfell for its bleak landscapes and desolation. Others seek to return to the Material Plane, hungry to spread the darkness and evil of the Plane of Shadow.

Dark Portals. Portals to the Shadowfell manifest in forlorn places and the deep gloom of subterranean caverns. The dragons that lair in such places often discover these portals and find themselves transported to a new realm. Ancient dragons that sleep in their lairs for months or years at a time might find themselves spirited away, never knowing that a portal has formed without their knowledge as they dream.

Recast in Shadow. The transformation to a shadow dragon happens over a period of years, during which time a dragon’s scales lose their luster and fade to a charcoal hue. Its leathery wings become translucent, its eyes paling to pools of opalescent gray. Shadow dragons find sunlight abhorrent, and they are weaker in bright light than they are in darkness. Darkness makes the dragon fade to a spectral shadow of its former self.

The magical nature of dragons holds an attraction for the Shadowfell, which seems somehow to crave the might and majesty of these great reptiles. The Shadowfell also has a dispiriting effect on its denizens, such that the longer a creature remains on the plane, the more it accepts the plane’s malaise. As months and years pass for a dragon on the Shadowfell, it becomes aware of the transformation being wrought upon it, and yet can do nothing to prevent it.

Back in the World. A shadow dragon is so suffused with the power of the Shadowfell that even a return to the Material Plane can’t undo its transformation. Some shadow dragons attempt to lure other creatures from the mortal realm back to the Shadowfell to keep them company, at least until they tire of their guests and devour them. Others are happy to leave the Shadowfell behind forever, understanding that treasure and power are easier to come by in the Material Plane.

Blue dragons make their lairs in barren places, using their lightning breath and their burrowing ability to carve out crystallized caverns and tunnels beneath the sands.

Thunderstorms rage around a legendary blue dragon’s lair, and narrow tubes lined with glassy sand ventilate the lair, all the while avoiding the deadly sinkholes that are the dragon’s first line of defense.

A blue dragon will collapse the caverns that make up its lair if that lair is invaded. The dragon then burrows out, leaving its attackers to be crushed and suffocated. When it returns later, it collects its possessions — along with the wealth of the dead intruders.

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:

• Part of the ceiling collapses above one creature that the dragon can see within 120 feet of it. The creature must succeed on a DC 15 Dexterity saving throw or take 10 (3d6) bludgeoning damage and be knocked prone and buried. The buried target is restrained and unable to breathe or stand up. A creature can take an action to make a DC 10 Strength check, ending the buried state on a success.
• A cloud of sand swirls about in a 20-foot-radius sphere centered on a point the dragon can see within 120 feet of it. The cloud spreads around corners. Each creature in the cloud must succeed on a DC 15 Constitution saving throw or be blinded 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.
• Lightning arcs, forming a 5-foot-wide line between two of the lair’s solid surfaces that the dragon can see. They must be within 120 feet of the dragon and 120 feet of each other. Each creature in that line must succeed on a DC 15 Dexterity saving throw or take 10 (3d6) lightning damage.

Regional Effects

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

• Thunderstorms rage within 6 miles of the lair.
• Dust devils scour the land within 6 miles of the lair. A dust devil has the statistics of an air elemental, but it can’t fly, has a speed of 50 feet, and has an Intelligence and Charisma of 1 (−5).
• Hidden sinkholes form in and around the dragon’s lair. A sinkhole can be spotted from a safe distance with a successful DC 20 Wisdom (Perception) check. Otherwise, the first creature to step on the thin crust covering the sinkhole must succeed on a DC 15 Dexterity saving throw or fall 1d6 × 10 feet into the sinkhole.

If the dragon dies, the dust devils disappear immediately, and the thunderstorms abate within 1d10 days. Any sinkholes remain where they are.