The players use two d12 Duality dice as their primary dice for action resolution, but as GM, you’ll instead use one d20. This creates a less predictable outcome for your rolls than those of the players; you’re just as likely to roll abysmally high or low as you are to roll a middling number, whereas rolling two d12s creates a more stable bell curve of results. When you succeed, it creates a new and exciting challenge for the players, and when you fail, it is a relief and a boon for the players. The swingy nature of the d20’s results helps to facilitate both of these experiences throughout a session (but if you ever want to increase the chances an adversary will succeed or fail, you can increase or decrease their attack modifier).

Making GM Rolls

When an adversary attacks a PC, you roll the dice to determine the outcome. This follows a similar process to PC action rolls (see “Action Rolls” in chapter 2), except using your d20 instead of two d12s:

• Roll your d20 and add the adversary’s attack bonus (along with any other dice, such as advantage or disadvantage).
• If the roll result meets or beats the target PC’s evasion, it succeeds and hits the target. Otherwise, it fails and doesn’t hit.
• On a success, roll the appropriate damage dice to determine how much damage the attack deals.

Critical Success

Cs aren’t the only characters who can roll a critical success–their adversaries can too! Whenever you roll a 20 on the d20, your roll automatically succeeds regardless of the PC’s evasion score.

If you critically succeed on an attack roll, you also deal extra damage. Start with the full value of the damage dice, and then make a damage roll as normal to add to that value.