I think your first graph is the most helpful for me. I haven't used the WoD system before, just D20 and a few homebrewed ones, but it seems like the success vs. Fail rate is the same for most systems. I really like that first graph though.
I agree with most of your comments. In my mind, the biggest downfall of this movie was Dolores Umbridge. While they came close, they just couldn't get that exquisite character. When I read the books, I felt incredible loathing towards her. In the movie, I find her annoying. I thought the new laws were definitely not presented in a way that made their impact truly felt.
This last book was a complete success. I think the two biggest reasons are:
1. it didn't follow the classic school year. That made me feel like really anything could happen. It suddenly added an even greater dimension of suspense as Harry was put in more real-world danger.
2. as you said, Voldemort really takes on his role as villain. Since he truly takes over the ministry and acts as Big Brother, it is great to see him finally using his infamous power to accomplish creepy goals.
Rowling finishes a classic.
The plots that I posted do take into account the 10-again rule. Since a 8, 9, or 10 produces a success, that means that there is a probability of 3/10 or 30% to gain 1 or more successes on a single die roll. You'll note that this is reflected on the successes probability chart. The probability of only 1 success for a single die is 0.2 + (0.1 * 0.7) or 27%. That requires a roll of 8, 9, or 10 but with the 10 followed by a re-roll of 7 or less. 2 or more successes require a roll of a 10 and then a subsequent roll of 8, 9, or 10. That equates to a probability of 1/10 * 3/10 or 3%. Again, that is reflected on the successes probability chart. Given the numbers that you give in your comment it appears that you have a fundamental misunderstanding of the probabilities for a 10-sided die, particularly with the added complexity of considering the potential for additional rolls.
I have not included the zero dice pool chance roll in my plots since it uses a different set of rules than a standard roll. Furthermore, since the probabilities surrounding botches can easily be subtracted from the zero successes probabilities, I haven't denoted them separately from the 0 success curve.
This is not quite correct, as you do not take into account the standard "10-again" rule, which states that if you roll a 10, then you gain a success and re-roll with the same rules. Therefore, for 1 die, you have an exactly 1/3 chance of success.
Additionally, just for clarification, the botch rule is if your dice pool is reduced to less than 1 die, you can still roll a "chance die", which succeeds on a 10 and "dramatically fails" on a 1. This is also subject to the 10-again rule, giving a 1.11111.../10 chance of success.
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