Any player can plunder any world that they own, although usually it is only the Raiders who will want to. (This is because any player other than a Raider will lose 5 points for the act. But sometimes it's worth it anyway, for instance to deprive an enemy of the benefits of a world.)

In order to plunder a world successfully, you must own the world at the beginning of the turn, and still own the world at the end of the turn--you cannot plunder a world in the same turn that you capture it from someone else, or in the same turn that someone captures the world from you.

Plundering a world drives its economy into chaos and renders it nonproductive for the next three turns (only two turns in an Advanced game). While the world is recovering from the plunder, its mines will not produce any metal, its industry will not build, and its population will not grow. Even the turns owned counter will not increase.

You cannot plunder a world while it is still recovering from a previous plunder.

In the RSW Client, the number of times a world has been plundered, and the number of turns remaining to recover from a recent plunder are clearly indicated on the World Detail panel. On the text-based turn report, both numbers are indicated with a string like Plunder=2/3 to indicate that a world has been plundered twice, and currently requires 3 turns to recover from a recent plunder.