As mentioned at the end of part 1, the thing that many of the White Wolf mechanic’s opponents dislike the most is that it’s unclear how much changing various features will change the chance of success. On any given roll, a GM:
- Can modify the character’s trait total, letting her roll more or fewer dice.
- Can vary the difficulty of the roll up or down, to alter how many dice are likely to come up as a success.
- Can set a threshold for how many successful dice are required to actually count as a success (and could even give free successes, essentially setting a negative threshold).
At difficulty 6, each die will come up a success roughly half the time. So -2 dice is similar to +1 threshold. Going from Difficulty 6 to Difficulty 8 nearly halves the number of expected successes, so its equivalence to dice and threshold varies by how many initial dice the player rolls. It’s complicated. It’s so complicated that every system after Old World of Darkness went to a fixed difficulty number, to at least make the probabilities slightly easier to calculate by limiting them to modifiers and threshold.
But, like I said, I’m a huge fan.
My enjoyment of this triple system is that, if used consistently, it creates a language for modeling the world that systems with a more defined interplay of probabilities can’t touch. Specifically:
- I use modifiers for effects limited to the character. Wound penalties already subtract dice when the character is injured. Enhancements in personal capability result in bonus dice (though this is applied inconsistently with merits). Effectively, when multiple player characters are attempting the same action, and one has situational modifiers, that’s accomplished by changing the size of the dice pool.
- I use difficulties for elements of the task/environment itself which should make things harder or easier. This is a pretty straightforward reading of many game systems, such as rolling against an opponent’s trait total as a difficulty. If something would be harder or easier for anyone, the difficulty changes.
- I use thresholds for situations where there are varying degrees of failure. If the threshold is 3 successes, getting 2 successes should be at least narrated differently than getting 0. Thresholds merge very well with extended actions, as a threshold may be nigh unreachable with a single roll, but successes accumulate over the rounds.
Ultimately, the thing to understand about the White Wolf dice system is that it’s rarely binary. 4-5 dice is a common pool for any action a player might willingly attempt, and that pool is statistically likely to get at least one success even at very high difficulties. The entire system creates a very interesting curve where the top and the bottom are always equal to total dice and 0, but the sweet spot in the curve varies based on difficulty.
In short, it’s not a system that expects characters to either simply succeed or simply fail. It’s a system where even minimally competent characters will almost always do something that resembles success, and it’s up to the GM to decide not how hard the task is, but how awesome the character needs to be to complete it. A GM in the system most effectively decides how to set the requirements for a task by asking:
- What is the minimum competency required to get an unqualified success on this task with an exceptional effort (e.g., is this something someone with 4 dice should be able to succeed at, even only a fraction of the time)? Set the threshold at that number.
- How often does that minimum competency succeed at the task? Set the difficulty low if it’s often, high if it’s rarely.
- What are the effects of getting successes but not quite hitting the threshold? If it’s exactly the same as completely failure, this task might not be interesting enough to roll for.
Well, at least you can do all that before 1s and 10s get involved…