Sunday, 30 September 2018

Luck Checks

There are two basic types of Luck checks:

(1) Roll under your Luck score. I usually say "equal to or under". This type of check can be modified by changing the die used along the dice chain - the larger the die, the less likely the roll is to succeed. The smaller the die, the more likely.

(2) Try to meet a target DC. In this case, the check can be modified by the die changing along the dice chain (with larger dice being better). The DC can also be shifted.

Why bother with two methods?

Using method (1), a PC with an 18 Luck succeeds 90% of the time. Using method (2), and a DC of 10, the same PC succeeds by rolling a 7 or better, or 70% of the time. Setting the DC to 15 reduces this to success on a 12 or better, or 45% of the time.

For method (1), the character's actual Luck score matters, so as Luck is used, the odds of success go down immediately. For method (2), only the attribute modifier matters, so while Luck use does affect chance of success, it does so in a more graduated manner.

Each of these has its uses.

Wait, why don't we use both methods with, say, Strength checks?

Good question. Why don't you?


  1. I've always disliked the DC mechanic, myself. "Roll under" is sensitive to every ability score point. Functionally it makes no sense for, say, a 13 and a 15 to be identical. Especially in systems where ability score losses are common (and gains should therefore be to, as rewards) I prefer to make the players lament every degradation possible. "Roll under" also works well with margin of success/failure intensifying or mitigating the result. One could do that with DCs but for some inexplicable reason it does not feel right. Also, It's nice when rolling a 1 is a triumph, and a 20 is a disaster, for variety's sake.

    1. The point is that the two methods accomplish different things. There is no reason why you cannot use both!