On dice and gifts

EDIT: Quick primer for those who have no idea what I'm talking about. The core of the nWOD system is rolling a certai number of d10s and counting 8s, 9s and 10s as successes. Most rolls benefit from the "10 again" rule, which says that if a die comes up 10, count the success and roll it again. Certain special abilities can grant a "9 again" on some rolls, meaning that if the die shows a 9 or 10, count the success and roll the die again. 8 again works the same way, except 8s, 9s and 10s are rerolled.

So, when I got to thinking about kiths and their abilities, I wondered about the difference between a bonus die and 9 again and 8 again. My math-fu is weak, but a little perl trickery revealed the numbers, and I found them interesting. Now, I note that these probabilities probably got cranked out by the math nerds as soon as the New WOD corebook came out, but I don't have the will to dig for those numbers. As a result, this is all pretty new to me. Anyway, the first exploration looked like this.

Pretty simple, and moderately intuitive. The breakpoints are clearly visible. Eight dice is the break point for 9 again. Below eight dice, gaining an extra die is more beneficial, but after eight dice, the benefit from 9 again is more pronounced. At eight dice it's equally appropriate to go either way. The impact of 8 again kicks in much sooner. With only four dice, it becomes more potent to get 8 again than an extra die.

Bottom line, if your diepool is small, you want extra dice. If it's high then then you want an X-again, and 8 again is scary-potent. But because its on a curve, there's no simple equivalency. If your pool is high, you want x-again, but if it's low, you want bonus dice. But even that's not entirely simple.

Bonus dice also help offset penalties, something that x-again does not do at all. If you're under a lot of stress, x-again will not help you much, but bonus dice can keep you from being stuck with nothing but a chance die.

On the other hand, x-again increases your chance of an exceptional success (5+ successes) dramatically. How dramatically?
So is it a wash? Kind of. +1d/9 again, +2d/8 again are probably roughly equivalent in a purely mechanical sense, but that's only half the story.

The two types of bonuses represent a kind of essential difference that you need to keep in mind when you give a kith one or the other. Practically speaking, an extra die or dice means that the character should not suck at the activity in question. They'll always have at least a little capability, even if they don't invest in it. In contrast, x-again pays out in relation to how much the player invests in the pool. The character can suck at the task in question if they don't pursue it, but if they _do_ pursue it, the rewards escalate as the return on the investment compounds. If the character's going to be good at something, this is the path to make them very good.

As a shorthand, think of bonuses as talent and x-again as mastery. The person with talent can do more with less, picks it up more easily and so on, and can deal with adversity more handily. In contrast the person who has mastered the task has taken longer to get there, but is prepared to truly excel. When you're giving an ability, are you giving extra capacity (bonus dice) or the potential for greatness (x-again). Choose wisely.