Tarrasque

The tarrasque was the most terrible creature known to inhabit the Prime Material Plane. The beast was a full tall and  long quadruped with a long tail, reflective carapace, and two large horns on its head. Supposedly, there was only one tarrasque, which slumbered within the world's core. No one could predict when it would next awake.

The tarrasque was irreversibly tied to the Prime by its nature. As a result, the most one could hope to do was put the creature to sleep within the core, holding it off for a while longer. However, ancient texts seemed to indicate that there might be a way to finally and ultimately deal with the creature, if one could somehow deceive it, luring it into another plane and sealing it there.

Description
The tarrasque was an enormous abomination, roughly the size of an ancient dragon, with two long horns extending from its forehead, a thick carapace, mighty tail, many spikes covering its large body, and a wide, toothy maw. The tarrasque also had two small eyes, but it did not rely on these for its primary method of sensory perception—if they were blinded or removed, it was effectively unhindered. The tarrasque was impossible to frighten or charm and had resistances to every kind of damage imaginable. It moved at a speed roughly half again that of a human, either while walking on the surface, climbing a height, or burrowing through the earth.

Behavior
Although the tarrasque was indisputably a force of pure destruction, it was not truly evil or even chaotic by nature, lacking the consciousness necessary for it to take a moral stance. As a result, it was merely neutral in alignment.

Abilities
The tarrasque had many unusual abilities gifted to it by its creators. Among the most terrifying of these was its ability to ignore any natural resistances its victims had, cutting right through them with its deadly attacks. It also had the ability to dramatically hinder the ability of creatures within of it to fly, reducing their speed substantially while also bringing them down to a maximum altitude of twenty feet, which put them within the beast's reach.

The tarrasque had the ability to instill nearby creatures with terrible fear, rendering them incapable of action. It was also immune to the ill effects of fire, poison, or disease. It was generally immensely difficult to injure. Some scholars even claimed that they were immune to all manner of psionic attacks.

Origin
The history of the tarrasque was controversial. Most persons were wholly unaware of the tarrasque's existence and those that did know of it were unsure about its origins, which they surmised to be anything from its actual creation to it being the weapon of an ancient and evil cabal of wizards. Most dismissed these theories, however, as unproven musings. More important was that the tarrasque rarely left evidence or witnesses, so dangerous was its nature.

Some sages argued that the tarrasque was created by the primordials as a weapon of destruction during the Dawn War, with the purpose of undoing the stability instilled in the world by the gods so that the primordials could remake it. Fortunately, the primordials created only one tarrasque.

Another theory was that the tarrasque was but one specimen of an entire population of the creatures living on the planet Falx, which was located somewhere in another crystal sphere. Falx had several hundred creatures that were either the same species as the tarrasque of Toril or else an (unfortunate) example of convergent evolution. According to this view, Toril's tarrasque had simply been transported or summoned to Toril from Falx in ancient past.

History
A unique tarrasque known as the Sleeper dwelled in the continent of Katashaka in ancient times. She was worshiped, and fed sacrifices, by the ancient Tabaxi tribe of humans and reigned over their lands. In Tabaxi legend, one season, the Sleeper desired vengeance against an ancient enemy and summoned the greatest warriors of the nine tribes to follow her into battle in Mhairshaulk (c. to c. ). Apparently defeated, the Sleeper returned in a rage and went on a rampage on the Night of Feasting, before finally returning to sleep. She would awaken twenty-three more times, ever more angry and hungry. Finally, on the next Night of Feasting at the end of a millennium,, the next sacrifice, Oyai, was blessed by Ubtao and empowered with magic, right before the Sleeper awoke and came to devour her. But she used the magic to halt, crush, and slay the Sleeper.

In the final years of the first empire of Netheril, a tarrasque's lair (known locally as the "lair of the sleeping beast" in what would be southwest Anauroch) was under heavy guard by Angardt barbarians whose shaman's prophecies told of the beast's imminent awakening. In the, adventurers hired by the archwizard Karsus came to cut out the tarrasque's pituitary gland, which was to be used as a spell component for the casting of Karsus's avatar. A gold dragon named Dracolnobalen, who protected the Angardt tribe, provided the adventurers working for Karsus with a liquid that she claimed would keep the tarrasque from waking again once applied to its body.

In the, a mage summoned a tarrasque through a ritual that required the heads of seven adult dragons to complete. It was defeated by the crew of the Realms Master.

Ecology
The tarrasque was an eating machine while awake, capable of swallowing creatures of roughly giant size whole. When roused, it would, by its design, eat quite literally the entire world, including plants and animals. Fortunately, it would only be active for a week or two before it returned to its slumber to sleep for five to twenty months, although, once every decade or so, the tarrasque would stay active for several months, after which it would sleep four to sixteen years, unless disturbed.

Usages
Legend had it that one could yield a vast number of gems from a tarrasque's upper carapace by treating it with acid and then heating it in a furnace. Other legends spoke of dwarven blacksmiths being able to forge metal from the tarrasque's underbelly by mixing it with adamantite and the creature's blood.