Whenever you are in the same location as other player, such as the Interactive Court or Jousting Fields, you can challenge another player to a duel. This can be to the death, with a Herald in attendance, unless quarter is granted (in which case a ransom must be paid). You cannot duel to the death without a Herald or Sysop presiding as the game will only allow you to duel until you pass out without them removing the safeguards.