Stacking advantage / disadvantage

[Nagol]

I would prefer to allow multiple sources advantage and disadvantage to stack so that one state is not immediately canceled by the other.

I don't want to use increasing pools for d20s though since (a) handfuls of dice need to get sorted and (b) the effect quickly pushes the results to the extremes, so I came up with this:

Count the number of sources of advantage and disadvantage. The highest total provides the state of the roll. Subtract the lower total from the higher to determine your net effect number. A tie means the state is normal.

If the state is either advantage or disadvantage then roll 2 dice instead of 1.

For advantage, the result is the higher die. If the result is below your net effect number, it becomes your net effect number.

For disadvantage, the result is the lower die. If the result is higher than (21 - net effect number), it becomes (21 - net effect number).

For example, Abe is under a lot of pressure. He has 3 sources of disadvantage and has managed to get only 1 source of advantage. Abe's roll is under disadvantage with a net effect number of 2. Abe rolls 2 dice and chooses the lower. The result can't be over 21 - 2 = 19.

This way the table can seek out multiple sources of advantage / disadvantage and the results stay mostly bounded. The extra instances of the state start to nibble away at the extreme outliers.

Comments? Math issues?

 

[Uskglass]

I used to feel the same: to me having 1 source of Disadvantage against 2 sources of Advantage would result in a net of still having Advantage. Right?
Then I thought a bit more thoroughly about it and I started to see the rational behind not allowing multiple instance of either one of the other to stack: maintaining dramatic tension.

Going towards higher levels, characters will have increasing ways to obtain Advantage multiple times, potentially overcoming any source of Disadvantage.
But by not allowing any stacking beyond one step in either ways, that means that even a single Disadvantage cannot be turned into an Advantage: you may offset it at best, but you are still gonna feel it.

Point is: it can be perfectly fine to mathematically add all instances, and that will likely gives better granularity, but I think I can see the reasons why they have it working as it is in the book.

 

[Umbran]

This way the table can seek out multiple sources of advantage / disadvantage and the results stay mostly bounded.

I am not sure that it is desirable to have the party seeking multiple sources. The game has largely gotten *away* from, "find every bonus you can" constructions, leading to bounded accuracy. This keeps combat pretty fast. If you give them some *other* form of bonus to seek, we get back to the old form - instead of trying to stack +2 here, +1 there, you're trying to stack advantage. It becomes another arms race, another source of min-maxing, more required adjudication and interpretation.

 

[Uskglass]

It becomes another arms race, another source of min-maxing, more required adjudication and interpretation.

Yes, I think you nailed it.
Ultimately, preventing the stacking makes life much easier for the GM. If he/she wants to impose a Disadvantage, because it would make for a more dramatic and exciting situation, then just needs to come up with one source for it, rather than several to counter all the Advantages players may be able to pull out to turn the Disadvantage into an Advantage anyway.

 

[Li Shenron]

It has to be noted that there is often quite a difference between skills/checks and attacks/saves.

Stacking bonuses in 3e irritated a lot of people, but in the context of skills/checks it didn't just serve the purpose of improving the odds to your favor (which it does with attacks/saves) but also and sometimes mainly the purpose of letting you reach a higher DC, that was otherwise impossible.

Unfortunately advantage never increases your max result, no matter how many you stack. So with this house rule you only achieve the benefit of increasing the odds.

IMO it's already quite too easy to gain advantage in 5e, so I'd proceed with caution before using this house rule... at least don't allow actual "stacking" i.e. don't allow 2 sources of advantage to let you roll 3d20 and take the highest, or 3 advantages equal 4d20. Stop at checking if the sources of advantage are more than the sources of disadvantage, and roll max 2d20 in that case. IOW, you can say that advantage and disadvantage cancel each other on a one-on-one basis, but overall the result is just net advantage, net cancel, or net disadvantage.