Advantage and Disadvantage
Some abilities will grant you Advantage or Disadvantage. When you have advantage, roll your dice pool twice and select the best result. When you have disadvantage, roll your dice pool twice and select the worst result.
For non-player entities (NPCs) with advantage or disadvantage, the game master (GM) will flip a coin to decide whether an NPC succeeds at their intended action.
Having advantage from more than one source does not allow you to roll your dice pool more than twice–and the same for disadvantage. However, advantage and disadvantage can cancel each other out so you end up rolling your dice pool only once. In cases where you have an uneven number of sources of advantage and disadvantage, you would benefit or suffer from the roll modifier with the most sources.
Example