Whenever a character attempts to overcome a challenge, they must roll the appropriate attribute against the difficulty set by the narrator. Unlike traditional RPGs, the difficulty of a task is always rolled by the narrator instead of being a static number. Difficulties can be as low as d4 or as high as d20.
If you have an advantage, you roll two dice and take the higher result. If you have disadvantage, you roll two dice and take the lower result. Advantages and disadvantages do not stack, but they do cancel each other out.
Advantage and disadvantage only affect the first roll of a challenge, not any subsequent rolls if one of your initial dice results in the maximum and you choose to roll a higher die.
You may attempt to help an ally on a challenge by making the same roll they're attempting. If you roll an even number, you provide them with a +1 bonus on their roll; however, if you roll a natural 1, you subtract -1 from their roll.