cerberus , who had been waiting obediently at the side of the altar , sprang into battle at the cue from its master , tearing into the multiworm with all five sets of jaws , shaking his heads rabidly back and forth , tearing the conjoined vermian monstrosity to shreds with his black fangs , avenging himself upon the monstrosity that had held his leash in bondage just an hour before .