Ahh yes, the die of fate. An old concept I once started but eventually forgot the rules for and would forget to run. Its a completely otpional rule that is used to spice of the gameplay. There is no set of rules for if it lands on a number. Like if it lands on a 20 you don't become god, or a 1 you die instantly. Its more like it determines how lucky of an encounter you run into. The rule is simple, all odd numbers are bad encounters, events, or bad luck. All even numbers are good encounters, events, or good luck. The higher the number the more good or bad the thing encounter, event or luck is and the lower it is the more more mild. So 20 is the best result and 19 is the worst, getting a 1 or a 2 is just something really insignificant happens. Dungeon Masters who use this will normally roll the die of fate at the beginning of a new map. No stats effect the die of fate, its just something that is random every time. When using it the encounter, event, or luck must be related to the map or quest.