Misfortune
Fate | Curse | Earth
To play this, you need an Earth Neopet. When this Neopet's controller rolls a die for a contest it's in, all rolls other than a 6 count as 0.
19/150 HatIC HoloFoil
This is a fairly nice curse, except for all those times where you find that either you or your opponent need a 6 to win anyway. However, it's fun to play this in an arena with a few Reactor Cores, especially if you have a Villain in there too :P
Putting it on a Grarrl Gladiator will strip away his ability to win when rolling a 5 :D
If you're playing Earth, this is your way to go, but Dark is far better off with the Nightstones and Maintenance Tunnels.
Ratings:
I don't think this is the most devastating of the 6 curses, but it can definately come in handy. Sadly, it's earth, and earth isn't currently one of the most popular types. But, it still earns a 3.6 of 5.