Sure the Tarrasque originally came from an old french legend. But the beast in that legend seems a lot more like a wimpy drake, than the Tarrasque we know and love from the MM.
So instead of returning to that legend for plot ideas, why not go to the REAL source that inspired the MM Tarrasque?
Special tanks to IMDB.com for assitance.
1. Tarrasque!
Testing of magical weapons of war has awakened the slumbering tarrasque, who is now laying waste to the country. One lone wizard possesses an artifact that can destroy the beast, but will also atomize all life in the vicinity. Can this wizard be convinced to use his ultimate weapon, or is the cure really worse than the disease. Co-starring Rayburr the Half-Orc Bard as special guest narrator.
2.The Tarrasque Raids Again!
The wizard's ultimate weapon was ultimately useless. While the tarrasque was gone for some time, it has now returned, more powerful than ever. And it has brought another beast it's equal in destructive force along for the ride. These two colossal forces of nature collide in combat, and their battle threatens he safety of the kingdom. Can the beasts be drive off somehow?
3. Tarrasque vs. Legendary Ape
The tarrasque once again menaces the kingdom. If only there was some other enormous beast to drive it away. Perhaps the stories that tell of a Legendary Ape worshipped by saveage primitve tribespeople are true? Rumors tell that the Ape has a penchant for elven maidens, can beauty woo the savage beast into helping drive off the tarrasque?
4. Tarrasque vs. the Faerie Vermin
The tarrasque is up to his old tricks again, marauding about the coutryside. It must be stopped! The adventurers must act as delegates to the twin faeries and entreat them to send the giant flying vermin against the tarasque. Sould the tarrasque defeat this fey moth, perhaps the twin faerie princesses can send the moths caterpillar children to finish the job their parent started?
5. Tarrasque vs. The Three Headed Dragon
The princess suddenly vanishes from her coach while travelling one day. She soon reappears, claiming to be an emissary from another plane. She tells of dire portents signifying the appearance of an evil extraplanar three-headed gold dragon. Are her warnings true? Who summoned this dragon? Could the tarrasque somehow defeat this new extra-planar threat?
6. Tarrasque vs. Outsider X
Outsiders appear in the kingdom asking permission to take the tarrasque back to their home plane. It seems their plane is plagued by an evil three-headed gold dragon, and they want to use the tarrasque to destroy it. In exchange they offer the kingdom the cure for all disease, as well as great magic and wealth. However, with the tarrasque now under their control these outsiders reveal their true colors and set both the dragon, and the tarrasque against the PC's
7. Tarrasque vs. The Epic Chuul
An enemy kingdom has been capturing slaves and taking them to heir forced labor camp on a remote island. The slaves have no hope of escape, or rescue, as they slavers control an Epic Chuul that destroys anyone besides them that approaches the island. Legend says he tarrasque also slumbers on this island. If the PC's could find and awaken the tarrasque, it just might be ale to destroy the chuul as well as the evil slavers!
8. Destroy all Tarasques!
After ages of predations by marauding monsters, the kingdom has finally managed to corral the tarrasque, and all other colossal monsters on one secure island. Things are going fine, until marauding outsiders release the tarrasque, a Legendary Roc, a Three-Headed Gold Dragon, and the moth-like Faerie Vermin as a diversion to their establishing a secret base beneath the kingdom. Stop the monsters! Stop the outsiders!
9. Tarrasque vs. the Gelatinous Cube
Recent industril pollution from the cities magical industry has somehow created a horfying fiendish epic gelatinous cube! Worse yet, the terifying ooze can fly, and is spreading acidic mist over the kingdom, melting people in the streets. Can the tarrasque and the PC's deal with this contaminated threat?
10. Tarrasque vs. the Father of all Hook Horrors
Fiendish Otsiders plan to conquer the world using the Father of all Hook Horrors and a fiendish three-headed gold dragon, , which they control from their secret headquarters inside the head of the trrasque idol at a nearby temple. The only thing that can stop them is the combined efforts of the Tarasque, and the PC's!
11. The Tarrasque vs. Underdark Vermin
Denizens of the underdark have sent the Father of all Hook Horrors and a Legendary cockroach to devestate the surface world. Can the PC's use their new Colossal Adamantine Golem to trick the tarrasque into helping destroy the threat from below ground?
12. Tarrasque vs. the Iron Tarrasque
Outsiders bent on global domination have contructed an Iron Golem replica of the tarrasque, and are attacking the Material Plane. With the help of a colossal Hound Archon and the real tarrasque, the PC's must repel these evil invaders.
13. Terror of the Iron Tarrasque!
Those wacky outsiders are at it again. With the help of a disgruntled local wizard, they have salvaged their Iron Tarrasque from the bottom of the sea, and enslaved a colossal acquatic T-Rex to take their revenge on the PC's and the tarrasque. Stop them at any cost!
14 Tarrasque vs. The Titanic Tendriculous
A crazed wizard has used his magic to combine a portion of the tarrasques powers with a simple rose. The result is a titanic regenerating thorny poisonous Tendriculous. At the same time, eveil agents from a neighboring kingdom threaten to awaken the tarrasque unless the secret of creating other such titans is revealed to them. The spirit of the wizards daughter must direct the tendriculous to defeat the tarrasque, while the PC's manage the enemy agents.
OK, enough silliness. I just can't do the rest of them.
Last one ...
15. Tarrasque! (Redux)
A neighboring kingdom decides they need to have a tarrasque of their very own. So the get some earthworm wizard and magically alter a lizard. However, the lizard looks ridiculous, is smaller, has none of the tarrasque's mighty powers or charming personality. No one is impressed.
