The information here was sourced from Roll20 Wiki; please refer there for details, or to resolve ambiguity.
Firestorm includes a chat line command for rolling dice, which is designed for role playing games.
At its most basic, the syntax is: rolld <number of dice> <number of faces> in nearby chat. Examples:
Modifiers may be added to this, but only one per roll. Valid modifier types are
These are standard sttack modifiers. For example, you might know that to roll an attack roll you need to roll a “D20 plus your attack modifier”. So you would just type rolld 1 20 + 5. If you hit and you need to roll 3d6+2 damage, you would just type rolld 3 6 + 2.
Normally when you perform a roll, rolld reports back the total value of all the dice rolled, plus any modifiers. Some game systems, though, work by rolling a set of dice versus a target number, and then adding up the total number of successes instead. Rolld uses the greater-than symbol > to indicate when the roll is greater-than or equal-to >= the target number. The less-than symbol < is used to indicate when the roll is less-than or equal-to ⇐ the target number.
For example, you might be performing an action that requires a target number of 3, and you get to roll 3 d6's to see how many successes you have. With rolld, you would do rolld 3 6>3. Note the inclusion of the greater-than symbol to indicate that this is a target roll versus 3. rolld will show you each dice that was rolled, and then tell you the number of dice with a value of 3 or greater (note that ties with the target number count as a success). You can also roll less-than target numbers, for example rolld 10 6<4, which would give you a success for each dice rolled that is equal to 4 or less.
rolld supports exploding dice (you may also know it as “rule of 6”, “rule of 10s”, or “acing” depending on your game system). With exploding dice, if you roll the maximum number on the dice (a 6 with a d6, a 10 with a d10, etc.) you get to re-roll again and add the additional roll to your total for that roll. If the additional roll is also a maximum number, you get to keep rolling.
To perform a roll with exploding dice, just add an exclamation point after the number of sides in the formula. For example, rolld 3 6! would roll 3 d6 dice with exploding re-rolls. You can also define the exploding point for the dice using the greater-than and less-than symbols. For example, rolld 3 6!>4 would explode on any dice greater-than or equal-to 4. /rolld 3 6 !3 would explode only if a 3 is rolled.
This is a special style of exploding dice where the the additional rolls for each dice have 1 subtracted from the roll. To do this, add a p after the exclamation mark. So for example to roll 5 d6's, you would do rolld 5 6!p.
Several systems require that certain dice be rerolled.
To use reroll, just do rolld 2 8r<2. rolld will roll 2 d8 and reroll any 1s or 2s, dropping the original die value. If reroll for a specific value is needed the comparison operator can be left off. rolld 2 8r8 will reroll any 8s. > and < can be used as comparisons and the r suffix can be specified multiple times.