Crag Dragon

Occasionally, beings that delve into the earth in search of riches find something else instead. A voice in the stone. Some are drawn deeper and deeper, to the source of the voice. Winding its way around the core of the world, Ulu’duun the Earth Wyrm whispers secrets of the universe as it carves the Sunken Path. This titanic primordial serpent of earth and stone warps the essence of lesser beings that are enlightened by its presence. Crag dragons are former true dragons that have made contact with Ulu’duun and have been transmuted by the energies of elemental earth. A mighty fusion of draconic and elemental essence, they draw power from the fundamental components of the material plane itself.
Craggy Behemoths. Crag dragons are extremely sturdy creatures with bulky bodies and massive heads. Their powerful limbs end in black iron-infused claws, perfectly designed to burrow through earth and rend flesh. Ferrous spikes sprout from the crown of the head down the neck from a thick motley of shale, rust, and mud colored scales. A crag dragon’s toothy maw is built like an oversized hippopotamus, with jagged tusks and a broad, shovel-like jaw that can scoop dirt and crush boulders or bones with ease.
       Crag dragons lay eggs of solid stone. Rather than hatching, the egg itself slowly takes the shape of a wyrmling until it is fully developed and mobile. Over its lifespan, a crag dragon’s hide thickens as it assimilates metals and minerals from its environment. Those who reach adulthood are stony fortresses of muscle and scale. Encountering one of these hulking beasts is like facing a mountain with wings.
Masters of Earth. Crag dragons are able to exhale petrifying energy and possess innate magical control over earth. They can also transmute their bodies into earthen objects for indefinite periods of time. From this form, a crag dragon can observe the world and communicate telepathically, all while hidden in plain sight. One might take the form of a gargoyle overlooking an urban square, a jade bracelet worn by an agent of the Sunken Path, or even a pesky pebble in a peasant’s shoe. This transmutative power can be used by crag dragons to spy on enemies, deceptively escape combat encounters, or survive an inhospitable environment in suspended animation.
A Voice in the Stone. Crag dragons possess a special form of communication, known as Stonespeech. A crag dragon can form a telepathic connection with any creature within a few miles of itself, so long as both the dragon and the creature are in contact with the same earthen surface. Adventurers wielding sentient magic items or worshipers communing with their god at a shrine may be unwittingly stonespeaking with a crag dragon. Crag dragons will maintain this illusion to bestow guidance and shape the world from a hidden vantage. It may take ages for a dragon to grow bored of their ruse and reveal its true nature. A creature exposed to Stonespeech for an extended duration is slowly transmuted by it, much in the way the crag dragons were shaped into their semi-elemental forms by contact with Ulu’duun. These creatures might find themselves attuned to elemental earth, gaining traits such as a magnetic sense of direction, lithodermic growths, or claustrophilia. Crag dragons will subtly guide creatures towards the Sunken Path to unlock these primordial powers.
Hoarded Secrets. Crag dragons are lorekeepers, prizing esoteric and ancient knowledge. Their hoards are vast libraries of tomes, scrolls and stone tablets that contain the secrets of the universe. Crag dragons will boldly embark on multiverse-spanning adventures to discover new information to add to their collection.

A Crag Dragon’s Lair
Crag dragons dwell in mountains, where they burrow deep into natural cave systems. They prefer regions with active tectonic activity or a suffusion of elemental energy. Their lairs are often laid out vertically, with chambers at many different altitudes. One entrance might be on the side of a sheer cliff-face or snow-blown mountain peak, while the other is hidden in a fungal cavern far underground. Any opening to the surface will usually be inaccessible to creatures that lack flight or extraordinary climbing ability. Occasionally, crag dragons will center their lairs around rifts to the Earth Plane, with a portion in each dimension. Crag dragons like to display their burrowing and stoneworking prowess by sculpting each chamber of their lair into elaborate shapes.
       The challenge rating of a legendary crag dragon increases by 1 when it's encountered in its lair.

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:
Jagged Earth. The dragon causes the earth to quake and become uneven. The ceiling, floor, and walls of the lair become difficult terrain until initiative count 20 on the next round.
Planar Fissure. The dragon cleaves the ground at a point it can see within 120 feet of itself. A line along the ground that is 50 feet long and 5 feet wide originates from that point. Each creature in that line must make a DC 15 Dexterity saving throw, taking 13 (2d12) bludgeoning damage on a failed save, or half as much damage on a successful one. Additionally, 2d4 dust mephits emerge from the fissure and immediately take their turns. The mephits are hostile to the dragon’s enemies and obey its commands. On initiative count 20 of the next round, any remaining mephits die in a sudden death burst.
Voices in the Stone. The dragon telepathically whispers to one creature using stonespeech. 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.

Regional Effects
The region surrounding a legendary deep dragon's lair is altered by the dragon's magic, creating one or more of the following effects:
Elemental Interference. If a creature casts the plane shift spell within 6 miles of the lair, there is a 50% chance that they will end up in the Elemental Plane of Earth instead of the intended destination.
Miraculous Memory. Creatures within 6 miles of the lair find it much easier to recall past experiences and information. The memory alteration and elimination effects of the modify memory spell are temporarily suppressed and Intelligence checks are made with advantage while a creature is in the region.
Rugged Wildlife. Beasts within 6 miles of the lair have unusually thick hides with a stony appearance. These creatures have resistance to nonmagical bludgeoning, piercing, and slashing damage.
Shifting Ground. The earth within 6 miles of the lair seems to have a mind of its own. Observant creatures will notice the ground rumbles as if breathing, landmarks rearrange themselves, and tracks vanish from the dirt. Creatures have disadvantage on checks made to navigate this terrain.
Surreal Scenery. Rocks and boulders within 6 miles of the lair take on fanciful shapes, animal forms, and complex dioramas of scenes from the dragon’s memory.

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

Stat blocks for Wyrmling, Young, Adult, and Ancient Crag Dragons as well as lair actions, regional effects, and supplemental art included.