I was crunching some numbers, with the goal of finding a way to provide a more consistent marginal chance of success in encounters against higher level NPC's, and hence a more enjoyable experience. These encounters tend to be common, and NPC modifies tend to be high, especially in the premade adventure I am running (age of ashes), and my players are frustrated feeling that they are fishing for 20's to hit or be effective.
My goal was that the marginal change of success probability be approximately 5% for each step in difficulty. Of course this can only be an approximation with a single die roll for resolution.
I found that the following modifications to a D20 gets within 4%.
1->-9
2->-2
3-> 0
Middle numbers the same
17->18
18->20
19->23
20->30
I am thinking of getting some custom dice printed. Does anyone have any comments or suggestions before I try that? They are not terribly expensive, but they are not super cheap either.
