Additive Advantage [5th Edition House Rule]

[Before I begin, I want to reference this article (and especially its chart) from The Online Dungeon Master. His was the first attempt I saw back in the playtest to math out Advantage bonuses, and I’m fairly sure nothing in the math has changed since then.]

On the whole, I am a fan of the new edition of Dungeons & Dragons. I cannot say as much for some in my gaming group, who made it through the playtest largely indifferent and/or uncertain about the whole thing. One point that earned some vocal displeasure was part of the rule concerning Advantage. This is the rule that causes them consternation, from the final playtest document (I’ve bolded the key text):

No matter how many times you gain advantage or disadvantage on the same roll, you roll only one additional d20.

If you have advantage and disadvantage on the same roll, the advantage and the disadvantage cancel each other out. This rule applies even when you have advantage or disadvantage from multiple sources. For example, if two effects give you advantage on a roll and one effect gives you disadvantage, you have neither of them for that roll.

Here’s the problem, they say: this is too abstract, even in a game of abstract combat. Something isn’t just advantageous or disadvantageous; advantage can be greater or lesser depending on all the circumstances. First, if an opponent is restrained and stunned, it should be easier to hit than if it’s just restrained, they say. Second, even if the attacker is Disadvantaged, the restrained and stunned opponent would still be easier to hit than the merely stunned one. The current Advantage/Disadvantage rule goes too far in abstracting the combat situation from reality.

I’m half in agreement with them. Left unchecked, a stacking Advantage roll could lead to situations where players find ways to roll three, four, or five d20s on an attack, making the roll practically moot. On the other hand, players feel like they’ve “wasted” a power or ability if it ends up granting Advantage on a creature that’s already been dinged with such an ability, regardless of whether or not the power or ability has additional effect. So I think that, if this rule remains unchanged in the final game, I’m going to invoke my first permanent house rule.

Additive Advantage is a pretty simple idea, one that takes the rather abstract concept and makes it a little more granular, a little more tactical, while still preserving game balance. It is essentially a trump system. It works like this: when both Advantage (ADV) and Disadvantage (DSV) are to be applied to a roll, determine the number of conditions and effects that grant each to that roll. If the number of Advantages and Disavantages are equal, they cancel each other out. If there are more Advantages to the roll than Disadvantages, then the roll retains Advantage (1dADV). If there are more Disadvantages to the roll than Advantages, then the roll retains Disadvantage (1dDSV). There can never be more than a single Advantage or Disadvantage die added to a roll.

So, for example, if an attacker is prone, but he’s attacking an enemy who is restrained, then there’s a single Advantage and a single Disadvantage applied to that roll. They cancel each other out and the attacker would roll a straight d20.


If, however, the prone attacker were attacking an enemy who was both restrained and stunned, then the attacker would actually gain Advantage on the roll since the number of Advantages (2) is greater than the number of Disadvantages (1).


Remember, the rule remains that only a single Advantage or Disadvantage die is rolled regardless of the number of conditions. For example, if a rogue is sneak attacking but is doing it while squeezed in a tight space and intoxicated against a wizard that has an Aura of Antipathy active (don’t ask me why, players sometimes get stupid ideas), the rogue would still suffer Disadvantage on the roll.


“But wait,” you say, “Doesn’t this still throw off the math, because now players will be getting Advantage more and thus hitting more?” Not really. What it does is potentially increase the frequency of Advantage. The per-roll hit math remains the same. Plus, it’s also increasing the potential frequency of Disadvantage, too; I like to think those balance one another. They just make for more dynamic combat.

Further, even if it’s increasing the gaining of Advantage, it’s not making Advantage freakishly frequent; instead, it is just adding some tactical nuance to the gaining of Advantage. With Additive Advantage there’s potential benefit in a combat situation to creating a second Advantage, because the more Advantages the attacker has, the more likely they will be to retain the upper hand that Advantage gives them even in a situation where they become Disadvantaged … and the more the DM will want to try and layer on the Disadvantages to keep players on their toes.

I’ll report back here to the blog as I play with this idea more.



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