Iron dragon

Iron dragons were intelligent and deadly dragons that preferred to subdue rather than kill intruders. They were the most powerful of the ferrous dragons.

Description
Iron dragons were a larger variety of dragon, with wrymlings being at least long and great wyrms being as much as  long (body length, tail length ). They had broad, almost shovel-shaped heads with multiple thick, backwards-pointing horns, and large plates that resembled shark fins ran down their spine. Their scales were a glossy, metallic black that, after adulthood, began to take on silver highlights; great wyrms' scales looked like moonlight on a dark, rippling pool.

Personality
Seeking information about the world, the iron dragon would wander the world in the guise of humanoids. Iron dragons were the highest ranked and most powerful of the Ferrous dragons and would dwell in the same areas as red dragons. This would lead to an extreme hate between the two dragon types, the Red considering the Iron inferior and the Iron in turn considering the red a stain on the reputation of Dragonkind.

This changed with the Spellplague, as they then shared territory with the Green dragons in the dense forests and hills. This rivalry for shared preferred territory saw the Iron dragons outwitted by the greens.

Abilities
Iron dragons possessed many different abilities common to the true dragons, such as darkvision and blindsense. They could assume an alternate form, that of an average-sized animal or humanoid, three times each day. Great wyrm iron dragons could, once each day, turn creatures to iron in a manner similar to the flesh to stone spell.

Iron dragons also had innate spell-like abilities. By the time they were at least young they could replicate heat metal three times each day, juveniles gained stone shape twice each day, by adulthood they could replicate detect thoughts twice each day, ancients could replicate transmute rock to mud twice each day, and old ones could replicate wall of iron twice each day.

Additionally, iron dragons were known to have two different breathe weapons: a cloud of sleep gas, and a cone of electrical sparks. The cloud of sleep gas was typically measured at long,  wide, and  high, while the sparks formed a cone about  wide at the dragon's mouth and   in diameter at the far end.

Like all ferrous dragons, iron dragons also possessed metalsense, a peculiar ability that allowed them to sense both the location and amount of any nonprecious metal within at least of them (as wyrmlings; great wyrms could sense it up to  away). This proved a great hinderance for anyone trying to sneak up on them while carrying any weapons or armor made of steel or other nonprecious metals.

Combat
Iron dragons preferred to avoid killing intruders, instead subduing and interrogating them.

Lair
Iron dragons sought large iron deposits deep in mountains or large hills to build their lairs prior to the Spellplague. Constructing tunnels and traps in their lair for enemies to stumble upon. After that cataclysmic event they seemed to prefer dense forests or broken hills to aid its large form in ambushing prey.

Habitat
Iron dragons needed iron for food and for reproduction, as such they needed large amounts of iron and hoarded it. This got them in to conflict with other creatures trying to mine the ore. After the Spellplague they ambush-hunted large game or intelligent humanoids depending on their alignment.

Notable Iron Dragons
There were some known iron dragons in the Realms: in the Sunrise Mountains there was a whole family lairing. In the mountains north of the northeastern end of Icelace Lake resided a particularly angry one; they could also be found in the peaks south of Taak Lake, in the Glittering Spires, and in the Giant's Belt Mountains.