[Ghostcat]

In Unwritten legends, you can attack anyone you want. However, it almost never happens. The kinds of people that enjoy being jerks usually don't stay long. People can be charged with assault and murder if the attack happens in the King's territory, and it takes a very long time to be a threat to most of the player characters.

Oh, and you don't get much for it. PC's keep their stuff on death, so the most the slayer would get is some exp, and arrested or beaten.