Table of Contents

Dominions Random Number (DRN)

Most skill checks use a Dominions Random Number, or a DRN. This includes virtually all Damage rolls, Attack rolls, Missile Hit rolls, and so on.

The DRN is two six-sided dice. A lower-case "drn" is one six-sided die. Any dice roll described as an "XdY" (i.e. 1d4) without saying it's open-ended is closed.

What makes this different from regular six-sided dice rolls? Well, Dominions Random Number dice explode; if you roll a 6, you make it a 5, and then you roll that die again. The extra roll is added to your total. You continue to roll until you stop rolling 6's. This is called an "open-ended" roll in-game, while regular rolls are known as "not open-ended" or "closed".

Understanding the DRN

Due to how the DRN works, there are few skill checks that are utter guarantees, and determining what the result of a roll will be is even more difficult.

drn Math (One Die)

You could zoom in on the odds of an open-ended six-sided die's results an infinite number of times, but let's just say you only expand twice at most:

Out of 216 Closed Rolls…

  • 36 will be 1's (16.67%)
  • 36 will be 2's (16.67%)
  • 36 will be 3's (16.67%)
  • 36 will be 4's (16.67%)
  • 36 will be 5's (16.67%)
  • 36 will be 6's (16.67%)

Average: 3.5

Out of 216 Open Rolls…

  • 36 will be 1's (16.67%)
  • 36 will be 2's (16.67%)
  • 36 will be 3's (16.67%)
  • 36 will be 4's (16.67%)
  • 36 will be 5's (16.67%)
  • 6 will be 6's (2.778%)
  • 6 will be 7's (2.778%)
  • 6 will be 8's (2.778%)
  • 6 will be 9's (2.778%)
  • 6 will be 10's (2.778%)
  • 1 will be an 11 (0.463%)
  • 1 will be a 12 (0.463%)
  • 1 will be a 13 (0.463%)
  • 1 will be a 14 (0.463%)
  • 1 will be a 15 (0.463%)
  • 1 will be at least 16 (0.463%)

Average: 3.930 (if the 16+ roll is ignored; ~4 otherwise)

DRN Math (Two Dice)

Out of 1296 Closed Rolls…

  • 36 will be 2's (2.778%)
  • 72 will be 3's (5.556%)
  • 108 will be 4's (8.333%)
  • 144 will be 5's (11.11%)
  • 180 will be 6's (13.89%)
  • 216 will be 7's (16.67%)
  • 180 will be 8's (13.89%)
  • 144 will be 9's (11.11%)
  • 108 will be 10's (8.333%)
  • 72 will be 11's (5.556%)
  • 36 will be 12's (2.778%)

Average: 7

Out of 1296 Open Rolls…

  • 36 will be 2's (2.778%)
  • 72 will be 3's (5.556%)
  • 108 will be 4's (8.333%)
  • 144 will be 5's (11.11%)
  • 180 will be 6's (13.89%)
  • 156 will be 7's (12.04%)
  • 132 will be 8's (10.19%)
  • 108 will be 9's (8.333%)
  • 84 will be 10's (6.481%)
  • 60 will be 11's (4.63%)
  • 51 will be 12's (3.935%)
  • 42 will be 13's (3.241%)
  • 33 will be 14's (2.546%)
  • 24 will be 15's (1.852%)
  • 15 will be 16's (1.157%)
  • 12 will be 17's (0.926%)
  • 8 will be 18's (0.617%)
  • 7 will be 19's (0.54%)
  • 3 will be 20's (0.231%)
  • 4 will be 16's with another roll (0.309%)
  • 4 will be 17's with another roll (0.309%)
  • 4 will be 18's with another roll (0.309%)
  • 4 will be 19's with another roll (0.309%)
  • 4 will be 20's with another roll (0.309%)
  • 1 will be a 20 with two more rolls (0.072%)

Average: ~8 (assuming the extra rolls add either drn average)

Dueling DRNs

Most DRN rolls are in opposition to another DRN roll. The Damage roll, for example, is opposed by a Protection DRN roll. The Attack roll is opposed by a Defence roll, the Penetration roll to make many magic spells work is opposed by a Magic Resistance roll, and so on. In these three cases, a base value (typically matching the name of the roll) is added on to whatever the result is, and what happens next is determined by the value.