Pyroclastic Dragon

(From 3.5e Draconomicon: The Book of Dragons - 2003):

Pyroclastic dragons are creatures of elemental fury, embodying the forces of fire, earth, and rumbling thunder that move earth and shape continents. They are native to the Bleak Eternity of Gehenna, an infinite plane of volcanic earthbergs and infernal lava. 

A pyroclastic dragon is solidly built and powerfully muscled, conveying a sense of immovability. Its scales resemble fractured obsidian and glowing magma, forming a mottled pattern of reds, oranges, blacks, and grays over its entire body. Its large wings seem almost to be made of ash, but despite their flimsy appearance they are quite capable of bearing the dragon’s great weight aloft. 

Pyroclastic dragons enjoy swimming through magma, but they make their lairs in caves carved out of volcanic rock. When they venture to the Material Plane, they live only in volcanic regions. 

These dragons enjoy the taste of meat but can also subsist on a purely mineral diet. 

Combat: Pyroclastic dragons have all the subtlety of a volcanic eruption—they may simmer and hiss for a time, but when they erupt at last their fury is unmatched. 

Young and older pyroclastic dragons’ natural weapons are treated as magic weapons for the purpose of overcoming damage reduction. 

Breath Weapon (Su): A pyroclastic dragon has two types of breath weapon, a cone of superheated ash accompanied by crushing waves of sonic force (dealing half fire damage and half sonic damage) or a disintegrating line. Creatures within the area of the line must succeed on a Fortitude save or crumble to ash. (Creatures that successfully save do not take any damage.) 

Spell-Like Abilities: 3/day—produce flame, sound burst; 1/day—fire storm, incendiary cloud, meteor swarm, power word, stun, pyrotechnics, shatter, shout, wall of fire, wall of stone.

(From 4th Edition Draconomicon: Chromatic Dragons - 2008):

No dragon better reflects the fury of the Elemental Chaos than does this one. Dwelling in the plane’s most violent regions, pyroclastic dragons can survive in places inimical to other life. They thrive on a diet of molten ores and minerals, but they savor roasted flesh whenever they can get it.  A pyroclastic dragon is a mountainous creature composed of molten rock contained by a thin crust of cooled stone. Its craggy maw gapes to reveal a whitehot core. It has the general shape and features of a red dragon, but its body vents poisonous gases from the numerous rents and fissures that split its stony hide.

Pyroclastic Dragon Lore: A character knows the following information with a successful Arcana check. DC 20: Pyroclastic dragons settle in the calderas of active volcanoes. They swim about in the lava, sometimes diving deep into the magma veins to see what can be found below. The mere presence of such a dragon causes the earth to rebel: Venomous fissures split the ground, while tremors roll out from wherever the dragon goes. 

Pyroclastic Dragon Tactics: A pyroclastic dragon is an unsubtle opponent that explodes into violence when provoked. It unleashes its breath weapon the first chance it gets, coating its victims in molten rock that cools, slowing and eventually halting its enemies. The dragon uses tremors against any that have not been so incapacitated. It then uses an action point to shatter its foes with its powerful bite and jagged claws.