1d = 1 die; 2d = 2 dice; etc. GURPS uses this abbreviation, for instance, because all GURPS dice are d6, so there's no point in putting a 6 after everything. Quicknickel, if your custom dice just return numbers, then just use Rollable Table rolls to roll multiple custom dice. Suppose your Rollable Table is called CustomDie. It produces the results of rolling 1d. To roll a single die, you use: /roll 1t[CustomDie] If you want to add multiple custom dice rolls together, change the number in front of the "t": /roll 2t[CustomDie] /roll 3t[CustomDie] Not only will it sum the custom dice, it'll show the individual results of each die as well.