Many factors can make a task easier or more difficult to accomplish. These factors may be stated in the rules, derived from a character’s attributes, or arbitrarily imposed by the GM based on the situation. When advantage or disadvantage applies to a task, it is resolved by rolling multiple d20s and taking the highest or lowest result, depending on whether advantage or disadvantage is imposed.
The GM must first determine which factors provide an advantage and which impose a disadvantage. If multiple factors apply, advantages and disadvantages cancel each other out on a 1-to-1 basis. For any remaining factors, roll an additional d20 for each, taking the highest result if the remaining factors provide advantage, or the lowest if they impose disadvantage. For example, if 3 factors impose advantage and 1 imposes disadvantage, after canceling out 1 factor on each side, the roll would involve 3 d20s made with advantage (the initial roll plus 2 extra for the remaining advantage factors).
Example Advantage and Disadvantage
Player: “I’m going to use my ‘Song of Diversion’ power to try and confuse the ogre before it attacks, imposing disadvantage on its next attack.”
GM: “Good move! But remember, the ogre already knocked you prone, which gives it advantage. It’s also in a ‘Battle Rage,’ which gives it another advantage.”
Player: “Right, so my disadvantage will cancel out one of those factors.”
GM: “Exactly. That leaves one remaining advantage from ‘Battle Rage,’ so the ogre will roll two d20s and take the higher result.”
Player: “Alright, let’s see how bad it is.”