Trortipose the Tormented's Tremendous Travelling Tortoise

From the introduction:

Trortipose was a blood-thirsty barbarian sorcerer of great power who rampaged across the known world in a gargantuan battle-tortoise the size of a Tarrasque. He has appeared once again, but anyone foolish enough to remain in the area has noticed that the vast tortoise now moves erratically and no warbands pour forth. Perhaps Trortipose is absent or no longer able to control the beast? Perhaps now is the time to gain access to the tortoise (which is said to be hollow) to put an end to Trortipose’s tyranny, and – of course – liberate any magic treasures that still remain.