I have to call you developers out on this one.  I'm rather annoyed that you would implement a setup like this.  I'm not going to explain it all cause you guy's want to keep it a secret from your players (but a lot of players already have found out how to abuse this broken system). I'm just going to tell it to you straight, many MMO's have tried to control rare drops/encounters in various other games, and the same conclusion is always met. You can't penalize your good players, cause your scare