When he was still young, the dragon was put in the cave by the Moors, who wanted to avenge themselves on the Christians for expelling them from the region.  The animal grew until he became a powerful beast, who, on his nocturnal forays into the surrounding countryside, devoured flocks and shepherds, devastated the farms and terrorized the local people.  The town of Terrassa offered a substantial reward to whoever could free them from this terrible menace.  Many knights, monks and soldiers tried to kill the Vibria, but as he was a cunning dragon who was very well versed in magic, nobody succeeded in subduing him.

Finally, Count Jofre, tired of the monster's excesses and of his subjects' complaints, decided to confront him.  Fully armed, and riding his powerful black steed, the Count set out for the dragon's cave.  The place was deserted, and only a black rook was perched on a branch.  But the brave Jofre was not taken in by the Vibria's tricks and he called him by his name: 'Vibria!'

The dragon immediately abandoned his bird disguise and turned into a horrendous winged beast who seized the Count with his sharp talons and tried to lift him off the ground and dash him against the rocks.  Without flinching, Jofre lashed out bravely against the dragon's scaly neck, and, when the beast opened his enormous jaws, he plunged his sword down his gullet, wounding him fatally.  However, the dragon still managed to fly off, but he fell headlong into the mountainside, which has been known ever since by the name of Puig de la Creu {the Peak of the Cross}.