All dice in DL are ordinary six sided dice, aka D6.
Whenever you are rolling dice in DL you will be looking to meet or beat a given number of successes.
This is done by rolling the pool of dice and comparing each of the rolled numbers to a target number. If the rolled number is higher it's a success.
By default, all dice succeed on a 4 or more (4+).
This can be modified by effects in game.
Dice in DL come in three different colours:
Black dice are the simplest, each dice that rolls above the target number grants one success.
Blue Dice are similar to black dice except that on a 6 they are worth 2 successes.
Red dice are the same as blue dice, except that on a 6 roll an additional dice and add the outcomes.
If that dice rolls a 6, add another dice, continue to do this until you stop rolling 6s.
As this is an infinite series it posed a problem for our modeling. Our program caps the number of additional dice at 10 per initial dice.