And not the fun kind.
Err, I mean. - Instead of killing players, there should be handcuffs and jails, where players can lack prisoners up until their trial. Instead of just butchering people we find who committed crimes. Handcuffs would make it so players remain logged in even if they logout so that trials can be held, and any punishment resulting from said trial can occur.
Of course, people COULD abuse this function. but people could also break out, breaking free of shackles would leave a scent but all the player who's been shackled has to do is find where theyve been attacked by the "griefer" hope hes offline, summon him and return the favor.
There could be different types of shackles with different strengths.