A black, granite like body sprouts cyan-colored crystalline projections that encase limbs, replace muscle, and accent armor. Standing on two legs with three pairs of shrunken forelimbs and remnants of wings that now form crystalline digging claws, this flightless gem dragon is a sight to behold, if not a sound.

Sonic Excavator. Even at rest, there is a constant low, droning hum as the crystal structures enveloping its body vibrate to produce sound. When burrowing, this hum grows to a completely deafening roar thanks to it utilizing these incredibly powerful soundwaves to pulverize rock and stone into fine sand with its claws and head, before using its many limbs and powerful tail to swim through the softened earth like a sea serpent through water.

Explosive Articulation. While most dragons have fierce roars that they use to assert dominance and communicate over distances too large for words, an Aquamarine Dragon's "roar" sounds more like pops, cannon blasts, and sonic booms. On the louder end of these sounds, many creatures can begin to feel the sheer force and pressure emitted by the dragons, even from very far away.

Meticulous Minds. Aquamarine dragons, if not known for their unique method of movement, communication, or countless other bizarre traits, are often recognized because of their strange behavior when it comes to collecting and sorting things. For example, most dragons have a single large room for their massive, sprawling hoards. An aquamarine dragon, however, would most likely have several dozen rooms with each one assigned a category for the stored treasures inside. It may encourage its servants and minions to sort and organize themselves by height, sex, species, or even something as specific as eye color, and the amount of conditions a single dragon can apply to these categories is limitless. When in a particularly disorganized or messy area, an aquamarine dragon may find itself grappling with paranoia, mania, and disruption to their ability to focus.

Wonderful art by @Endivinity on twitter!

An Aquamarine Dragon’s Lair

Aquamarine dragons lair inside of large mountains and caverns, preferring cool, damp locations with easy access to water. In fact, they desire access to water so much that they commonly choose smaller, colder, wetter locations than spacious, warm, dry locations, even if the latter would be far more comfortable. Using their incredible burrowing abilities, aquamarine dragons create dense, complicated networks of tunnels to connect their large main chambers, which they take pride in traversing as effortlessly as a minotaur in a maze.

Aquamarine dragons collect kobolds and other humanoids to work for it as servants and companions, however not all of these creatures may be willing. They furnish their lairs with plenty of spaces for their servants to rest, eat, and enjoy themselves more often than not, in addition to having large, spacious caverns dedicated simply to playing games, training its psionics, or eating. If you can think of a room that serves a purpose, even the most insignificant, the dragon has likely used its psionically-powered sonic excavation abilities to carve out a space to act as such. 

The incredibly dense latticework of tunnels and caverns that make up an aquamarine dragon's lair are not spared by its obsessive mind. Each room has a purpose, big or small, and this is most well-displayed with the sheer quantity of small rooms used to store the dragon's hoard. Each of the chambers are clustered around a central cavern that the dragon most often prefers to use as sleeping quarters, which allows it to be near its precious treasure in times of rest. 

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:

• Beguiling Whisper. The dragon telepathically whispers to one creature within range of the dragon's telepathy. The creature must succeed on a DC 15 Wisdom saving throw or be charmed by the dragon until initiative count 20 on the next round. A creature charmed in this way obeys to the best of its ability any command the dragon issues that isn't directly harmful to the creature.
• Thunderous Quake. A tremor shakes the lair in a 60-foot radius around the dragon. Each creature other than the dragon on the ground in that area must succeed on a DC 15 Dexterity saving throw or be knocked prone.
• Boiling Geyser. Water heated to a roiling boil by the inside of the earth erupts from a point on the ground the dragon can see within 120 feet of it, creating a 20-foot-high, 5-foot-radius geyser. Each creature in the geyser’s area must make a DC 15 Dexterity saving throw, taking 21 (6d6) fire damage on a failed save, or half as much damage on a successful one.

Regional Effects

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

• Small earthquakes are common within 6 miles of the dragon’s lair.
• Sinkholes open up within 1 mile of the dragon's lair on the surface or in neighboring caverns, but are rarely deep enough to lead into the lair by themselves.
• Sand and mud present within 1 mile of the dragon's lair becomes less dense and more airy, turning into quicksand that can easily trap unsuspecting travelers and animals.

If the dragon dies, these effects fade over the course of 1d10 days.