Some characters, like Doctor Strange and Felix Faust, have a special ability that uses a 20 sided die. But as you'll see, even with Probability Control, your odds aren't very good to get a specific result.

Related: Pow! Felix Faust

Let's take a look at Probability of the d20. (Note that some numbers are rounded)

Edit: [3] and [4] clarified to show unrounded values. Edit: Special thanks to R3411Y for pointing out a 1/100 of a rounding error

Remember, if you want a specific result, there is just a 5% chance that it will appear -- and a 10% chance it will appear with Probability Control. That's awfully small.

As such, this is where things get interesting, as Felix Faust has been a concern to many players.

There are 2 desired results from Felix Faust's d20 roll. The first is the RED JAR of CALYTHOS and the second is PROJECT THAUMATION.

Red Jar of Calythos is worded as "Give Felix Faust a free action. Until your next turn, action tokens are not removed from opposing characters. Felix Faust must roll his d20 on his next turn.".

For Project Thaumation, it's worded as "Give Felix Faust a free action. Until your next turn, opposing characters may only be given free actions. Felix Faust must roll his d20 on his next turn."

In reality, there, there is a third problem with Faust's d20 roll - he can get the "ANY" result, allowing him to freely choose either of the above. So, under this scenario there are really 3 possible die rolls you want -- but that probability is just 15%.

We cover Felix's problem in more detail over at Pow! Felix Faust

With Probability Control, it only goes up to 28%! And with two Probabilities, it's just 38.6%! Does this kind of probability warrant banning Felix Faust? You be the judge.

Note that this particular set of rules doesn't matter much anymore. Wizkids recently changed Probability Control with this official errata: "Probability Control may only be used on rolls that utilize d6s."