This set of dice are “nontransative”.  In other words the red one beats the green, the blue one wins against the red and the green one defeats the blue.

With this set of dice you can always have a 55% chance of winning.  First get your victim to pick their die, then select the die that beats it.  Here is a graphic showing why:

Red beats green, blue beats red, and green beats blue. This special set has 21 spots on each die and every face has a value between 1 and 6.  This is the most consistent winning set with those constraints, and it was found by Steve Hawtin.  The next step is to actually make a physical set.