Cumulative Advantage

Typically, multiple instances of advantage or disadvantage cancel one another out completely, and having any number of sources of one can be countered by a single source of the other. This variant rule is designed to allow sources of advantage and disadvantage to further influence one another, but not to stack, so having multiple sources of either doesn't end up being wasted.

If you have advantage and disadvantage on the same roll, instead of necessarily resulting in a normal roll, count up how many separate sources of advantage and disadvantage you have. If the roll has a greater amount of sources of advantage than disadvantage, then make the roll with advantage, or make the roll with disadvantage if the reverse is true. The roll is made normally if it has an equal amount of sources of advantage and disadvantage.

For example, if a ranged weapon attack is being made at long distance against a lightly obscured target, and the attack is made under the effect of the assess the situation at-will tech power, then the attack has two sources of disadvantage and one source of advantage, and would be rolled with disadvantage. If the target is stunned, then that is two sources of advantage and two sources of disadvantage, meaning the attack roll would be made normally without advantage or disadvantage. If an ally successfully uses the Help action on the target to grant advantage on your attack, then it has two sources of disadvantage and three sources of advantage, letting the attack roll be made with advantage.