I can't say, how often it will happen. I think, there are sometimes phases in which it happens very often, sometimes it won't happen for days, that a person is killed for no reason ...
The only way to avoid it, is to write a mail to
gods@illarion.de with the name, number, date, time of the pking, and perhaps some words or a small screenshot, so that Bror can verify in the logs, if the person has broken the rules and take the needed actions against the player.
It would be sad, if you will go. Most of the people, who play Illarion for longer, like to roleplay and prefer this style ... there are mostly the new ones, who didn't know, what it is and how to do it, which behave like PKs. But how should they know, when most of the games are hack'n slash games, where it is important to get in short time more and more powerful to beat the others out of the way. It is a process of learning this way of playing.
And for this, we need players, who will show them, how toplay a roleplaygame, another reason for you, not to leave ...
And with the next version will come an email-announcement, so that it will be more difficult to get in, if you won't play a role.