Here's the rough draft. I notice that the original article states "There were, at the time, at least 12 species of ferrous dragons. Two of the species are known to have been driven to extinction, but the names of the species are not known." That leaves four non-extinct species that have not been detailed. Should we come up with them for alternates?
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The ferrous dragons are true dragons that vary in alignment. However, they all follow a strict hierarchy and all serve a sovereign dragon of their kind, who in turn serves the Supreme Dragon. They possess all the abilities of the true dragons in the Monster Manual, and all possess telepathy. The sovereigns and the Supreme Dragon possess a telepathic link with other ferrous dragons. The following creatures will be featured:
Nickel Dragon (Dragon, CR varies)
Nickel dragons are the weakest of the ferrous dragons. The scales of the nickel dragon are a charcoal gray at birth, changing to a more metallic gray as adults. As the dragon continues to age, the metallic gray begins to show white until, as a great wyrm, no traces of the gray remain and the dragon is a bright metallic white. Its breath weapon is a cone of acidic vapors. Other abilities include water breathing, immunity to acid, spell-like abilities and spellcasting.
Tungsten Dragon (Dragon, CR varies)
The scales of the tungsten dragon are a deep forest green, flecked with brown at birth. The scales lose their brown flecks and take on a metallic sheen until they become a gleaming green as adults. This metallic sheen dulls considerably after this stage until turning into a dull, flat green as great wyrms. Its breath weapon is a cone of blasting sand. Other abilities include immunity to fire, spell-like abilities, spellcasting, and a spontaneous combustion ability.
Cobalt Dragon (Dragon, CR varies)
At birth, a cobalt dragon's scales are a deep, dark blue with odd patches of both lighter and darker blues. These colors remain throughout the dragon's life, changing only in respect to the sizes of the various patches as the dragon grows. Its breath weapon is a line of pure magnetic energy. Other abilities include water breathing, immunity to electricity, spell-like abilities, and spellcasting.
Chrome Dragon (Dragon, CR varies)
The chrome dragons have a remarkable resemblance to silver dragons, and many an
adventurer has met his end because of such a similarity. At birth, a chrome dragon's
scales have the appearance of tarnished silver. As the dragon ages, the scales begin to brighten until, as adults, the scales have the appearance of pure silver. The scales continue to change until reaching the old stage, at which point the scales resemble modern chrome, even to the point of showing one's reflection. Its breath weapons are a cone of freezing crystals and a line of solid ice. Other abilities include immunity to cold, spell-like abilities, and spellcasting.
Iron Dragon (Dragon, CR varies)
Iron dragons are born with scales of flat black. As the dragon ages, the scales begin to take on a glossy texture until as adults the dragon is metallic black. The scales continue to take on silver highlights until, as great wyrms, the scales look like moonlight reflecting on a rippling pool. Its breath weapons are a cone of sleep gas and a cone of superheated sparks. Other abilities include immunity to fire, alternate form, spell-like abilities, and
spellcasting.
Gruaghlothor, Supreme Dragon of the Ferrous Dragons (Dragon, CR 25)
Gruaghlothor resembles a great iron wyrm in every respect except for its tremendous size. He is on a par with Bahamut and Tiamat (in their non-deity incarnations). His breath weapons are a cone of sleep gas, a cone of superheated sparks, and a line of solid stone. Other abilities include immunity to fire, alternate form, spell-like abilities, and spellcasting. Additionally, Whenever Gruaghlothor dies, the iron dragon chosen to replace the former goes into a state of hibernation for one year. During this time, the chosen one undergoes a metamorphosis. When it emerges, it has become Gruaghlothor.
Sovereign Ferrous Dragon (Template, CR +0)
This is really a "mini-template", adding only a telepathic link with other ferrous dragons. It can be applied only to great wyrm ferrous dragons.
The article would also include a sidebar detailing changes to the half-dragon template to create half-ferrous dragons.