Secretive historians who lurk within the hearts of dead volcanos, emerald dragons are reclusive and cautious beings. They do their best to remain unseen, and even among most draconic worshiping circles they are almost mythical in rarity.
These notable loners have a smooth, polished gleam to their scales that gives them an almost unified appearance. These sloping scales lead up their bodies, ending in almost spear-like points as ridges along their spines and joints. Unlike most gems, the scales of an emerald dragon start as an almost transparent viridian. As they age, their scales harden and become more opaque while they also begin to mold to the muscles of the emerald dragon's body. This eventually gives their gem-like hide the appearance of a seamless suit of spiked armor, giving the emerald a ferocious appearance indeed.

Paranoia Of all dragons, emeralds are by far the most extreme in their isolation and suspicions of other beings, leading them to be the most paranoid breed of dragons. While often they have allies and underlings that they send out into the world, an emerald will not trust any of them with the true location of their lairs, preferring to meet at designated (if still secluded and private) locations that periodically change to ensure that, even if their contact is being followed, no ambushes will be waiting for them. An emerald will not have servants to clean their lair or keep it in order, preferring to do it themselves to ensure that nothing goes missing and that no one will divulge any of the dragon's many secrets. This paranoia and suspicion extends even to their mates and young, and even to these precious and beloved family members there are parts of the cavernous lair that are off limits. Female emeralds often change the layout of their lair after giving birth, to ensure that the memories inherited by their young will not be used against them at any point in the future.
Red dragons especially terrify the emerald, since the power and cruelty of the tyrant reds are known far and wide and the emerald, living most often in extinct volcanoes, comes into conflict over territory rather often with their chromatic cousin. The sight of a red of a similar age is typically enough to make an emerald abandon their lair and find a new home.

Historians Emerald dragons love collecting, studying and cataloging things of historical value, and they hire and maintain multiple networks of historians and spies to ensure that they can record history as it happens. More often than not, at least one emerald dragon will have their claw in the funding of an archaeological expedition, and if word reaches them that a group of intrepid adventurers is seeking to plunder an ancient tomb, the emerald will do their best to ensure that at least one member of the expedition is their (often unknowing) agent, so that they receive a full first-hand report. With all of their accumulated knowledge, the emerald dragon makes for a horrifyingly dangerous political enemy, and one of the most useful allies a leader or adventurer could have.

No breath Unlike the other true dragons, an emerald doesn't have a proper "breath" weapon. Instead of a supernatural flame or zone of frost, the magic of an emerald is built to release powerful, beyond-hurricane strength blasts of air that can blow apart rocks and bend steel, enough to cause harm even to the Terrasque. Their magic extends even farther, encompassing the air around the dragon. An emerald dragon has perfect mastery over the winds and clouds, and has far more control over the weather around their lair than most other dragons. Forcing an emerald dragon to fight is to literally invite the tempest, and arrows or even siege weapons tend to be as effective as a child's toys against this magnificent creature.

Sapphire allies About the only being other than their mate that an emerald will truly trust is a sapphire dragon. Emerald and sapphire dragons will commonly team up, with the emerald making a lair above the underground one of the sapphire and covering both the Underdark and overland with their watchful vigil. Such alliances are beneficial to both parties, and even the paranoid emerald dragon knows that there are more rewards than there are risks in seeking out and accepting such a partnership. This also has lead to an interesting phenomena; while cases of differing draconic colors interbreeding are heard of, for the emerald and sapphire dragon it is almost commonplace, and often just seen as a natural extension of the alliance. Children of such a pairing are raised by both parents, no matter how contradictory their teachings may sometimes be, and are often some of the most celebrated draconic generals and historians in the mortal world.

When they are not on the plane of earth with the other gem dragons, a crystal dragon is typically found in the northern and temperate mountain peaks of the world, where they have few natural predators beyond white dragons and the occasional kraken to contend with. They have no preference for coasts or dry land, and really just try to find some place where giants, and especially bigger, much meaner dragons, On initiative count 20 (losing initiative ties), the dragon takes a lair action to cause one of the following effects:

• A whirlwind of sand and debris is kicked up, picking up any lose rocks, logs, bits of hail or any other items on hand and slamming them into foes within the tempest. Enemies inside of a 20 foot cube must make a DC 15 dexterity saving throw, and are dealt 10 (3d6) bludgeoning, piercing or slashing damage (dragon's choice) on a failed saving throw, and half as much damage on a failure.
• A powerful gust of 30 mph winds blast in one particular direction, making movement and ranged attacks within the area far more difficult. Wind within 600 feet of the dragon blows away from it, forcing creatures within the area to roll a DC 15 strength saving throw at the beginning of their turn or treat the area as difficult terrain. Even flying creatures treat this area as difficult terrain. Ranged attacks made within this area have only half of their normal range. This lair action lasts for either one minute, or until it is used again.
• The dragon causes a sudden swell of wind that picks up one creature and tosses them back. One target creature in the dragon's lair must make a DC 15 strength saving throw. On a failure, the creature is lifted up 10 feet into the air and then thrown up to 30 feet in any direction of the dragon's choosing. Treat all movement caused in this manner as falling distance. If a creature collides with a wall, creature or other object in their path, then they are dealt an additional 7 (2d6) bludgeoning damage.

Regional effects
A legendary emerald dragon's lair is warped by the dragon's magic, creating one or more of the following effects.

• The dragon's cave is covered in glittering and dazzling jade, emerald and beryl. This gemstone extends just below the surface of the earth one mile from the edge of the dragon's mountain or fortress home, giving warning to any miners and architects in the area that they are treading on a dragon's territory. This gem grows around the root systems of plants, and trees or other deep-rooted foliage may plant roots within it without penalty. This gem disappears and becomes regular earth a month after the dragon's death.
• The weather of the area is often slightly off from what it normally is. Rains might not be as violent, or they might go unseasonably long. Winds might be dead within ten miles of the dragon's lair, or they might be a swirling tempest that kicks up a dust storm. The emerald dragon can actively control this effect, allowing them to channel and generate even violent lightning storms after concentrating on the effect for almost a day. They can also calm or weaken storms after an hour of concentration, giving them far greater control over the well being of local fauna than most other dragons, and bothering the arboreal green dragons a bit. Weather patterns return to normal the day the emerald dragon dies.
• The emerald dragon is connected to all flying vermin within ten miles of their lair, typically insects and birds (often songbirds and cicadas). They may receive telepathic communication from these creatures, and through this network the emerald dragon typically knows the general locations of any potentially hostile creatures that are approaching its lair. This connection causes the insects and birds of the area to be more alert to the presence of humanoids, aberrations, monstrosities and dragons. This heightened awareness disappears a week after the dragon's death.

reach them.

Lair actions
On initiative count 20 (losing initiative ties), the dragon takes a lair action to cause one of the following effects:

• All sources of light in a 60 foot cube are immediately extinguished, potentially casting the lair into pitch darkness. If this would extinguish all usable light in the lair, then even creatures with darkvision are unable to see on their next round.
• The dragon creates a 20 foot sphere of light on the ground, making it a painful area to look at when moved over. Creatures with eyes treat this sphere as difficult terrain. This sphere remains until the dragon dies or uses this lair action again.
• The dragon causes a spike of crystal to fly from the ground in an attempt to impale a creature. The dragon makes a ranged attack against one creature with a +7 attack bonus, and deals 10 (3d6) piercing damage on a hit.

Regional effects
A legendary crystal dragon's lair is warped by the dragon's magic, creating one or more of the following effects.

• The entirety of the lair slowly becomes more translucent and reflective, from the exterior in. This eventually turns the lair into a perfect prism whenever dawn or sunset strikes it.
• The walls of the lair give off a faint glow, creating dim light throughout the lair. The dragon can extinguish this light at any time it wishes. As long as the walls give off light, then the dragon knows if and approximately where any intruders or guests enter its lair.
• Faded images and shapes appear randomly in the air, drawn from the cherished memories of the dragon and cast along the walls of their crystalline home. These images are silent, and usually happy memories.

If the dragon is slain, the light disappears immediately and permanently, but no other effect will be reversed.