I have created the following compilation and readjustment to BECMI D&D of this creature...maybe it suits your purpose.
There are scars of the Tarrasque in the mountains north of Alfheim of its appearance in the Known World. (the Valley Gordo di Tarask(Elvish; Scar of the Tarrasque), The Hidden Crystal Valley, and the Valley of C'Kag..see here
Unique Dragons: Tarrasque (Tarrasqueus Uniqua)
by RobinAncient, ageless, and unstoppable, all know tofear the unrelenting devastation that is the tarrasque. A creature of legens, associated with the greatesty of heroes and the darkest of times, little is known of the beast widely held as the greatest of monsters. Reports of the monstrosity’s powers and ways to slay it have changed over time, but tales of its brute destructive force remain ever constant. Yet even the beast likely rumors and purported banes are comforts for those who must face that which is ruin unleashed.
Dragon| Tarrasque
Type| Dragonkin
....... |Biological Construct
Climate |Any
Terrain |Any
Frequency| Unique
Organization |Solitary
Activity Cycle| special
Diet |Omnivore (literally)
AL |N
NA |1
Languages |0
Spellcaster Limits; |na
Length| 50' long 30' high 20' wide (not including 36'tail)
ST |26
IN |2
WI| 4
DX |8
CO| 26
CH |6
AC |-3
AV|9
HD |70********
HP |300
MW |90'/30'
rush |150'/50'
THAC0 |-3
Attacks |1 bite
Damage |5d10 + sharpness
Attacks |2 claws 5' long
Damage |1d12 each
Attacks |2 horn attacks 7'long
Damage |1d10 each (x2 if Rush)
Attacks |1 Tail lash 36'long
Damage |2d12 + push away
Special attacks |Sharpness (negate AV)
................... |Cause Terror
.................... |once/T rush = trample 4d10
.....................|Crush 3d10 damage on anything steppped upon
Special Defenses; | Regeneration
Immune to; |0
Extra Vulnerable to; |0
Awake |1 on 30 chance (1 week onlY)
AM |0
Save as;| F36
ML |12
XP |112,750
TT |special
Body Weight 107.000 LBS
History
The Tarrasque is a legendary destroyer, but it was originally a biological construct. Around 3500 BC there was no Great One to guide and protect the Dragons, they had been nevertheless gaining power and knowledge through the Cerimony of Sublimation, and their breeds had continued to evolve, becoming larger and wiser. Magic became even more a part of their very being. A fellowship of powerful Dragon sorcerers was formed (The tale of the origin of the Gemstone Dragons comes from the Dragonlord Trilogy, where it’s related by the Great One himself: “In this time, there was a fellowship of powerful Dragon sorcerers who had observed the slow advancement of their race and wished to gather and direct the magic they would need to accelerate that natural process. They wished to evolve into higher forms rather than be content to wait for their descendants to inherit the power and wisdom that would be their birthright”. “I must confess that I was a part of their band, at first, for I was a cleric in the service of the Immortal Terra, and I supported anything that might benefit the Dragons. At first their desires were pure and noble. But in time they came to believe that they could become Immortals, and that became their ultimate goal. I argued with them, warning them that they expected too much, but they would not listen. And so I withdrew from my company. Many of these dragons travelled to and from a specific Outer Plane Veydra and found a source of powerful magic there; gems. In time these Dragon sorcerers worked this great magic upon themselves, but their experiment failed. They did not become true Immortals but were instead transformed into the gemstone Dragons.
Believing that they had the right as the most powerful being in the world to rule the world, they became to force lesser nations to their will. Eventually they made war with Blackmoor. They had observed the slow advancement of their race and wished to gather and direct the magic they would need to accelerate the Ceremony of Sublimation. They wished to evolve rapidly into higher forms rather than be content to wait the completement of the stages needed to inherit the power and wisdom that would be their birthright.
Embittered by the failure of their spells but emboldened by the fact now they were the most powerful creatures on the planet, the Gemstone Dragons began to think that, if they couldn’t rule the Multiverse, they had at least the right to rule the world. With time, words of the power of the Gemstones spread, and they began to force lesser nations and races to their will. Eventually, they realized that the main hindrances between them and the achievement of their goal were other Dragons and the Blackmoor Empire, which ruled most of Skothar and parts of Brun around that time.
Around 3200 BC the Gemstone Dragons devised a plan to eliminate both their adversaries at the same time, causing a war between the Dragons and the Blackmoor Empire. In the last years, the Blackmoor Empire had been battling against the Beastmen and had pushed them toward the North Pole; during the decades of war against the Beastmen, the Blackmoorian armies had passed through Dragons’ territories many times, and isolated squabbles against some Dragons had became frequent during the last years of the campaigns against the Beastmen. Thus it was even too easy to instil in the Dragons’ minds the fear that the Blackmoorian strategy was in the long run to get rid of the Dragons once and for all. On their side, the Blackmoorians thought they were the most advanced civilization on Mystara, and thus arrogantly felt they had the duty to gather together all nations and races under their own empire—and to crush those who opposed them. The men of Blackmoor were arrogant; history agrees on that point. They believed that the world would be best served if all nations and races were gathered together into a single large nation, and they naturally believed that nation should be their own. The Dragons wanted no part of such plans. They fought back and quite possibly found that they were stronger than they had expected.
War eventually broke out on a large scale. For the first time in thousands years, the Dragons were united against a common enemy and poured all their rage against it, ravaging cities, laying waste to fields and killing the human population. In their opinion, after millennia of scattering and decline which had allowed the human civilizations to grow, they were finally retaking what was theirs. Against the full fury of Dragonkind, Blackmoor’s might was in check, and the Empire found itself on the defensive for the first time in centuries.
The Emperor of Blackmoor, frightened to discover that his armies and weapons couldn’t defeat the Dragons, entrusted the war to his wizards. The men of Blackmoor employed their most powerful arcane skills to create armor and weapons capable of turning any physical or magical attack the Dragons could muster. Using their most powerful arcane skills and lores, they created a terrible biological construct, the Tarrasque. They used the bodies of several slain dragons, copiuous amounts of Gems, metal ores and biomatter, the combined hearts of Geonids and Rockmen, a tremendous amount of energy from magical and technological origin, and the summoning of an unknown (now at least) entity to posses and animate the body. And so the Tarrasque was created. With the destruction of Blackmoor the exact secret was obliterated, and luckily the creature could not ever be recreated. However, the creature could not be defeated eather, as it spawned itself anew everytime it was defeated (there are some mentionings in history where heros defeated the beast). The creature, being a construct is also unable to evolve, or spawn offspring. Whenever fully defeated, it will be gone forever. Some wizards, clerics and even Immortals have battled with the idea of destroying the ultimate destroyer, and only recently they devised that it needed a correctly worded Wish spell (as this is actually the only spell mortals and Immortals get from the Old Ones) is needed to banish the soul of the entity within from this plane back to its home plane (wherever that might be).
The body of the Tarrasque then will remain, where nature will erode and rot it away in time. No other creatures or constructs could ever be created from these remains, as they not only contain magic but also highly unstable energy from unknown technological or even technomantic (fusion of technological and magical) sources. It is certain that this technique will work, however, the Tarrasque is now somewhere hidden in sleep and won't resurface for some decades. And any attempts sofar failed because some parts of the creature (bits of blood or chopped-off flesh from the battle) recreated the creature after the heroes went away.
Description
By its physical build alone, a tarrasque might be mistaken for a dinosaur, towering more than 50 feet tall and measuring at least 70 feet from nose to base tail. It stands upright on its powerful hind legs, with its body thrust forward and its tail providingh a counterbalance. In general, it move much like a Tyrannosaurus, although its front limbs are significantely larger; while a tyrannosaurus has stumpy forelimbs unable to even reach its own head, the tarrasque’s arms are long enough to touch the ground as it stands erect, and in fact the creature has been known to “knuckle walk” in the manner of some apes.
Covering the tarrasque’s dorsal half is an exceptionally thick, highly reflective armored carapace covered in massive spikes, while twin horns of similar size and shape jut forth from the creature’s head. The horns are used offensively, while the carapace serves a defensive role—not only against physicals attacks, but also against many maghical attacks as well.
This carapace has been described as looking like “molten diamomd”(by those lucky enough to have encountered the creature and lived to tell the tale.), which accurately describes the carapace’s toughness, reflectivity, and overall smoothness. In truth, the tarrasque’s carapace is not made from diamond—molten or otherwise—having an unique composition.
The bodily processes of a tarrasque can readily digest all organic matter, living or dead, creatures and plants—even wood that has been painted or varnished. The lone destroyer’s immunity to poison leaves it unharmed by dyes, molds, other growths on decaying organic matter, and so on. A tarrasque has an expanding gullet that holds creatures and objects swallowed whole, which tumbles such devoured items around in a continuous spiral, working them down into a succession of three stomachs. These stomachs are among the most effective destructive engines in the Multiverse and little—even the most magical and powerful artefacts—can survive within. The uppermost stomach is a hot, wet place of tumbling stones and internal spines (the stomach wall seems lined with thousands of bony knife-blades) that breaks down large objects; its walls are durable and very strong, with moving knots of muscle that can literally punch, squeeze, and claw (with the spines) at swallowed items. This stomach can shatter large rocks down into smaller stones, break clods of earth into scattered motes, crack bark and bones, dismember, and puncture containers so as to spill out and separate the contents. Belts, fabrics, and ropes are typically sawn into shorter pieces in this stomach, and glass is shattered. Metal and glass shards are typically moved on swiftly to the deeper stomachs.
The middle stomach of a tarrasque is a churning, energetically pulsing fleshy cauldron of corrosive acid. Unique in all the planes, this fluid possesses a disjunctive property, capable of stripping the magical powers from consumed magics. Here everything breaks down.
The last stomach of a tarrasque is a long, winding, rhythmically-thrumming tune of great heat, where anything that surbvives the prevous stomachs—typically only the strongest and rarest metals and gems—meet its end. The acidic slurry boils of and is absorbed by the creature.
Combat
The tarrasque is a highly destructive creature. It needs to eat constantly and savors its desire to destroy in order to survive. As a result, it has many combat methods. It can attack with its tail, its claws, its spikes and horns, by stomping, by grabbing and by slamming its massive 130-ton body into opponents. The creature does not have a breath weapon, but it can swallow victims whole. It can inspire terror in people by charging or rushing. Its armor, in addition to giving excellent melee protection, can also deflect all manner of offensive spells, and the tarrasque has some regeneration abilities.
The only monsters that are more feared in combat are Immortals, the largest and oldest dragons, certain powerful outsiders (such as demon lords) and epic monsters.
The tarrasque is a killing machine and when active (see below) eats everything for miles around, including structures, all animals and vegetation.
Normal Attacks
Normal attacks are with its two forelimb claws (1d12 points of damage each), a sweeping tail lash (2d12 points of damage), a savage bite (5d10 points of damage plus acts as a sword of sharpness—negating any Armor Value—severing a limb on a natural attack roll of 18 or better), and two thrusting horn attacks (1d10 points of damage each).
Rush
Once every turn, the normally slow-moving tarrasque can rush forward at a movement rate of 150’/50’, making all horn attacks cause double damage and trampling anything underfoot for 4d10 points of crushing damage.
Fear Aura
The mere sight of the tarrasque causes creatures with less than 3 levels or Hit Dice to be paralyzed with fright (no saving throw) until it is out of their vision. Creatures of 3 or more levels or Hit Dice flee in panic, although those of 7 or more levels or Hit Dice that manage to succeed with a saving throw vs. paralyzation are not affected (though they often still decide to run away).
Extreme Damage Hitroll versus bad Armor Class
As the Creature has a negative THAC0 of -3, the damages are increased on creature having a worse Armor Clas than that. Use the following table todetermine if a character is hit and what extra damage is sustained with each attack. It is best for a DM to note the current AC of the playing character together with the extra damage to be sustained, for it is easy to lose track of this as characters often have different defensive spells at hand. From this total the Armor Value may be deduced with each attack if the character has any Armor Value, as normal.
Immunities/Defenses
The tarrasque’s carapace is exceptionally tough and highly reflective. Bolts and rays such as lightning bolts, cones of cold, and even magic missiles are useless against it. The reflection is such that 1 in 6 of these attacks actually bounces directly back at the caster (affecting him normally), while the rest bounce off harmlessly to the sides and into the air.
The tarrasque is also immune to all heat and fire, and it regenerates lost hit points at a rate of 1 hit point per round. Only enchanted weapons (+1 or better) have any hope of harming the tarrasque. The Tarrasque is totally immune to all psionics.
Habitat/Society
It takes a tarrasque mere moments to force what it consumes through its devastating digestive process. Despite the swiftness of this metabolism, the vast majority of energy is stored. While it takes a great deal of food to keep an actiber tarrasque sated, tarrasques are actually quite docile—this stored energy sustained them through deep, decades-long hibernations.
When preparing for such a hibernation, a tarrasque employs one of its most unusual and rarely witnessed abilities. Once fully glutted and ready to go back to its sleep, a tarrasque gains the ability to merge in the eart in much the same way as Xorens do; it burrows through stone, dirt, or any sort of earth except refined metal or continuous veins of pure metal as easily as fish swim through water, without disturbing or dislodging anything or leaving a tunnel or hole in its wake.
This lets the beast access subterranean caverns its bulk would normally not allow it to reach. Lacking a large enough cavern to lair in, it can become completely buried to be one with the stone (sharing space with solid rock, a condition referred to as ärnstone” by some dwarven sages. This is a way there is so much debate and mystery surrounding the location and nature of a Tarrasque’s lair.
While in ärnstone state, the beast does not suffocate, but sinks rapidly into a torpor in which its bodily processes slow and it hibernates until need for new nourishment aweakens it into the ”burrowing” state again. In damp rock, where mineral laden water percolate, and with as belly filled with the ruins of a lartgwe town or city, this need might not arise for as long as 50 years. In dry or caustic rock, or if the beast is disturbed by tremors (including the relatively minor vibrations of nearby rock or creature movements in the earth), shifts in temperature, or actual wounding (direct damage from the pick of a dwarven prospector, or the weapon of an adventurer, for example), awakening might come much sooner.
A tarrasque’s carapace and outer hide are clearly visible to earth merging or wuarrying creatures who reach one’s immediate vicinity. Earth merging creatures cannot merge into or through the volumne of earth or rock occupied by an arnstone tarrasque; its body seems “solid” to such creatures, who are deflected aside from it (this includes dwarven and nithian magical vessels that can travel through the ground).
A tarrasque comes out of torpor with astonishing speed if distiurbed, typically taking only 1d4+1 rounds to become fully aroused. While awakening, a tarrasque has the same propertoes and vulnerabilities as when sinking into torpor. A waking tarrasque is unpredictable; it might move away from the disturbance, turn to confront it, or “flee” at high speed for some time and then try to settle down into torpor again.
A tarrasque’s actions are all driven by one need; nearly insatiable hunger. It has an intellect just above that of an animal and instinctively sees other creatures as food, buildings as food, rocks and dirt as food, and so). Given its powerful regenerativbe abilities, it has little to fear from combat with most creatures, and even those that have the capability of killing it—like high-level spellcasters—don’t register as anything other than another potential source of food. Thus, a tarrasque never retreats from battle, no matter how events might turn against it.
A tarrasque is by no means an evil or vindictive force. It is no more a source of evil than a hungry wolf or lion, although this view is difficult to maintain by those whose homes, families and entire lives have been destroyed by such a ravenous beast. The only real enmity the tarrasdque ever feels towards its living victims is reserved for creatures capable of flight. Since the tarrasque has no method of ranged attack, any creature capable of flying beyond its reach has nothing to fear—a fact that annoys a hungry tarrasque to no end.
Once the tarrasque has its fill—a process that can normally take up yo a week, during whjich time it remains completely awake and continually alert—the creature begins to get drowsy and prepares for a long sleep. So long as it is not currently in battle (as its primitive brain refuses to allow it to depart from a fight while there is still living morsels to ingest), it finds the nearest chunk of solid rock big enough to support its massdive bulk and settles down for sa lengthy hibernation.
The tarrasque is a greatly feared creature. However, it spends most of its time dormant, sleeping deep in an underground lair . Its sleeping periods range from two to four months, to up to sixteen years. After these periods, the tarrasque awakes. Erupting from its underground lair, the behemoth starts on a rampage, terrorizing the nearby area, smashing every structure, devouring both plant and meat alike, killing anyone who opposes it, and ultimately turning the area into a barren wasteland. Only when the Tarrasque has been killed, or once it returns to its lair to sleep, is the land safe again.
The older the tarrasque gets, the longer its periods of sleep seem to last, sometimes eventually lasting for hundreds of years. Never, however, does the tarrasque weaken or lose its lust for destruction.
It is hoped that the tarrasque is a solitary creation, some hideous abomination unleashed by the dark arts or by elder, forgotten gods to punish all of nature. The elemental nature of the tarrasque leads the few living tarrasque experts to speculate that the elemental princes of evil have something to do with its existence. In any case, the location of the tarrasque remains a mystery, as it rarely leaves witnesses in its wake, and nature quickly grows over all remnants of its presence. It is rumored that the tarrasque is responsible for the extinction of one ancient civilization (Mogreth), for the records of their last days spoke of a "great reptilian punisher sent by the gods to end the world”.
Various mortal explanations of the tarrasque's origins exist: some claim it is a curse from the gods, while others say it was created by evil wizards.
In the Spelljammer series, the accessory Practical Planetology suggests the tarrasques soul originates from the planet Falx. Several hundred tarrasques live there in a docile state, where they are silicavores (rock eaters); upon removal from their homeworld their temperament changes to the violent, rapacious one better known elsewhere in the Dungeons & Dragons universe, it could be that the entity came from here.
Ecology:
Slaying of the tarrasque is said to be possible only if the monster is reduced to -30 or fewer hit points and a wish is then used. Otherwise, even the slightest piece of the tarrasque can regenerate and restore the monster completely. Legend says that a great treasure can be extracted from the tarrasque’s carapace. The upper portion, treated with acid and then heated in a furnace, is thought to yield gems (10d10 diamonds of 1000 gp base value each). The underbelly material, mixed with the creature’s blood and adamantite, is said to produce a metal that can be forged by master dwarven blacksmiths into 1d4 shields of +5 enchantment. It takes two years to manufacture each shield, and the dwarves aren’t likely to do it for free.
It is hoped that the tarrasque is a solitary creation, some hideous abomination unleashed by the dark arts or by elder, forgotten gods to punish all of nature. The elemental nature of the tarrasque leads the few living tarrasque experts to speculate that the elemental princes of evil have something to do with its existence. In any case, the location of the tarrasque remains a mystery, as it rarely leaves witnesses in its wake, and nature quickly grows over all remnants of its presence. It is rumored that the tarrasque is responsible for the extinction of one ancient civilization, for the records of their last days spoke of a “great reptilian punisher sent by the gods to end the world”.
It is fortunate that the tarrasque is active only for short periods of time. Typically, the monster comes forth to forage for a week or two, ravaging the countryside for miles around. The tarrasque then seeks a hidden lair underground and lies dormant, sleeping for 5d4 months before coming forth again. Once every decade or so, the monster is particularly active, staying awake for several months. Thereafter its period of dormancy is 4d4 years unless disturbed. The ratio of active to dormant states seems to be about 1:30.
Real World Mythology
The Tarasque is a fearsome legendary dragon from Provence, in southern France, tamed in a story about Saint Martha.