While it is assumed that Terra-Scale dragons originally migrated from the elemental plane of earth, they appear to function socially and physically like that of other dragons with the exception that their sole diet is derived from minerals within the earth. Young Terra-Scale dragons tend to be less picky with their diet, consuming stones and rocks that have their favorite mineral conglomerated within. As the dragon grows it becomes much more selective with the minerals it eats, sporting scales that become more and more refined and pure as a result.

Terra-Scale dragons almost exclusively make their homes within deep underground caverns or other large subterrainian networks, magically altering the environment into vast regions of crystalline or metallic structures than can span for miles. They have even been known to invade and take over lairs originally created by creatures such as Beholders. These dragons are most often discovered by unaware miners and archaeologists who stumble into their lair, awe inspired by the concentration of rare gemstones or metals that the dragon regularly consumes.

The presence of Terra-Scale dragons in an underground region represents an immense profit for miners who seek to brave the dangers of operating within the lair of such a creature. Unsurprisingly, they are usually assumed to become victims as stories are rarely told of explorers who ever traverse the beautifully crystalline caverns and return full-handed.

A Terra-Scale Dragon's Lair

Terra-Scale dragons live deep within underground caverns and other subterranean networks, magically altering the environment into vast regions of crystalline or metallic structures than can span for miles. They have even been known to invade and take over lairs originally created by creatures such as Beholders.

As a Terra-Scale dragon's hoard is equivalent in value as its own food source, these dragons fiercely protect their territory, viewing any unknown intruder as a threat that must be eliminated indiscriminately.

Throughout the lair complex, one might find abandoned mine carts and excavating equipment; the remnants of unwitting prey that stumbled in far past their welcome. 

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:

• Minerals matching that of the dragon's diet spring out of the ground, walls and ceiling within 120ft., forming large shards and spikes and causing the affected area to become difficult terrain. Creatures moving through this terrain take 2 (1d4) piercing damage for every 5 ft. travelled.
• 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. If the area is affected by the mineral growth of the previous lair action, shards fall from the ceiling onto the affected creatures, dealing an additional 21 (6d6) piercing damage on a failed save, or half as much on a successful one.

Regional Effects

The region containing a legendary red 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.
• Traces of the mineral favored by the dragon become more and more present in the form of geodes and outcroppings the closer one gets to the dragon's feeding grounds.
• Rocky fissures within 1 mile of the dragon’s lair form portals to the Elemental Plane of Earth, allowing creatures of earthen variety into the world to dwell nearby.

If the dragon dies, these effects fade over the course of 1d10 days, but the minerals that grow in the caves remain indefintely.