Write as NdS where N is the number of dice and S is the number of sides. Example: 2d6, 1d20, 1d100
Add or subtract a fixed value with +N or -N at the end. Example: 1d20+5, 2d6-1
Use khN to keep the highest N dice, or klN for lowest. This is how advantage and disadvantage work. Example: 2d20kh1 (advantage), 2d20kl1 (disadvantage)
Use dlN to drop the lowest N dice, or dhN for highest. Example: 4d6dl1 (ability score generation)
Use rbN to reroll dice below N once per die. Example: 1d20rb2 (Halfling Luck), 2d6rb3 (Great Weapon Fighting)
Use rmN to keep rerolling dice below N until satisfied. Example: 2d6rm3
Use mN to treat results below N as N. Example: 1d20m10 (Reliable Talent)
Use rmtN to reroll all dice if total is below N. Example: 4d6dl1rmt6
Prefix with label: to group by damage type. Separate expressions with spaces. Example: fire:8d6, slashing:1d8+3 fire:1d6
Use label:rmtN to reroll labelled dice if their total is below N. Use *:rmtN for all dice. Example: str:4d6dl1 dex:4d6dl1 *:rmt70