The Fyre Drake

Here's what it mostly looks like. It's featured in the latest chapter of "Path of The Unforgiven", 'Broken Masks'.

The Fyre Drake is a creature of primordial power, a relic of far more ancient times. Fueled by its internal combustion system, the drake can only live in temperatures cold enough to counteract the exothermic release of its body heat. Basically: it's so hot on the inside, it has to have cold to prevent its heat from destroying it from the inside out.

It's outer appearance is as imposing as you'd imagine. Thick scales of an iron-like material cover from had to toe, each of them rough and coarse to the touch. All over its body however, are open veins from which are vented the incredible heat that sustains it. The drake is as tall on all fours as the ceiling of the Canterlot throne hall, and long enough to span most of Ponyville. Remember the dragon the Mane 6 had to roust from the cave? It's that big. It has four legs that end in claws strong enough to crush stone, and big enough to hold multiple ponies in its grasp. The membrane of its wings absorb light, and as such, can eclipse any light on the opposite side of an observer.

Though it very much resembles dragons, it is a singular creature, as distinct from actual dragons as from ponies. Being such, it has no loyalty or kinship to any other living creature in the world of Equestria. It would see dragons as much enemy/prey, as anything else. while dragons are known to be bullyish, even cruel at times, even they would be hard pressed to match the ferocity and might of the Fyre Drake.

Its primary weapon is the Aubergine Flame. A fire that burns in a dark purple shade, and is in fact highly infused with raw, primordial magic so pure, that any magic of less potency cannot defend against it. The drake spits this flame from its maw, and can only use it in short bursts. If it has to use it for any prolonged periods of time, it must either conserve its employment, or wait several hours for it to replenish.

It was met in single battle by the First Son of Thule, Prince Æclypse over a thousand years ago, and was defeated when the prince drove a stone shard through its heart. In the aftermath, King Rubicon, ruler of Thule sent for the mage Star-Swirl the Bearded to devise a means to dispose of the remains. It is not recorded what method Star-Swirl used, but the body was safely confined.
------------------------------------------------------------------------------------------------------------------------------------------