Goddess Nemesi and her friend had an issue with this slave and they had to ensure that he got the message as soon as possible. That is why they went out of their way to trample the crap out of him. He had to feel the pain so they hard trampled his hands with their boots. They stomped on his hands and fingers and made him scream out in pain.
Goddess Nemesis needed to settle a score she had with this guy. She chose to do it with her hard trampling fetish and to make it even more interesting for her, she chose to invite her friends. Her friends helped her to hard trample the guy and to dominate him as cruelly as he needed to be hard trampled. He never messed up again after what they did to him.