What you choose to define, while perhaps interesting commentary on the human condition, isn't, alas, relevant to the current state of the law.
I'm not sure which game you're playing, but there aren't that many MMORPGS around, so I'm guessing it's World of Warcraft.
That said, and even if it isn't, most have this functionality, you simply highlight the person's name and click "ignore". In damages cases, even assuming you had one, you kind of have to work to mitigate how much you're damaged. Like, say, you can't stop in the middle of the street and get hit by a car to in turn sue them when you could have moved out of the way and prevented the whole thing.
Here, you can either use ignore on this person, or simply open a ticket with a game master if the person's conduct is outside of the game's Terms of Service or End User Licensing Agreement. If the person's conduct is in violation, the game masters will happily action that person's account. This is distinct from you have a claim of action in court though.

