Halfling's Lucky vs. (Dis)Advantage

[Greywander]

What happens when a halfling makes a roll a with advantage or disadvantage? How does it interact with their Lucky trait?

I can see potentially three ways of handling it:

When the final result is 1, you reroll both dice.
When the final result is 1, you roll 1d20 and use that instead.
When either die shows a 1, you reroll that die.

Lucky is at its strongest when you're at disadvantage (as you're more likely to roll a 1, both on the individual dice and on the final result), but it seems like it would be pretty weak when you have advantage, as it's very unlikely both dice will show a 1. The third option makes it a bit better, as if one of the dice shows a 1, there's a chance it will be higher than the other die after you reroll it. For example, if you roll a 1 and a 7 while you have advantage, then there's a chance that the rerolled 1 will be higher than 7.

[Lord Vukodlak]

As I understand it when you roll a one, you re-roll that d20 so the third option.

[Lyracian]

PHB P 173 says
When you have advantage or disadvantage and something in the game, such as the halfling's Lucky trait, lets you reroll the d20, you can reroll only one
of the dice. Vou choose which one. For example, if a halfling has advantage on an ability check and rolls a 1 and a 13, the halfling could use the Lucky trait to reroll the I.

[Segev]

This isn't specifically spelled out in the rules, and in at least one case is contradicted by the way that Sage Advice rewrote"clarified" the rules, but in all situations where there are multiple d20s being rolled from more than one special rule allowing dice substitution et al, I treat it as being done sequentially. The one exception I can think of is Elven Accuracy, which explicitly applies when and during an Advantage roll.

(Dis)Advantage gets applied first almost universally, because that's about the only one where you know you're rolling "extra" dice first. Then, you resolve the (dis)advantage, picking which of the d20s applies as your roll. Then, you evaluate whether, based on that die roll (which now is only one d20 result), whether you wish to apply (or can apply) other "reroll" or "extra die" mechanics. For example, if you have Halfling Luck and the final (dis)advantage result is a 1, you reroll the die. If you have Lucky and spend a luck point, you roll a new d20 and take either it or the one that you have settled on after resolving (dis)advantage.

I forget Portent's exact wording, but it replaces the entire roll, as well. So if you apply it before you roll, it doesn't matter whether the roll is at (dis)advantage or not; the Diviner foresaw the result and proclaims it. If you apply it after the roll, you apply it as the final result, regardless of how many dice were rolled to get there.

This treatment is a little complicated to write out, but the execution is simple and straightforward, because you're never asking which die you reroll or replace: it's always only one die result being manipulated at a time.

[Tharkun]

Halfling Luck specifies that if you reroll a 1 you must take the rerolled value. That means if you rolled a 1 on either die you reroll the 1 and then take the rerolled value.

[Zalabim]

This isn't specifically spelled out in the rules

PHB P 173 says
When you have advantage or disadvantage and something in the game, such as the halfling's Lucky trait, lets you reroll the d20, you can reroll only one of the dice. You choose which one. For example, if a halfling has advantage on an ability check and rolls a 1 and a 13, the halfling could use the Lucky trait to reroll the 1.

I just love these happy accidents.

[Greywander]

PHB P 173 says
When you have advantage or disadvantage and something in the game, such as the halfling's Lucky trait, lets you reroll the d20, you can reroll only one
of the dice. Vou choose which one. For example, if a halfling has advantage on an ability check and rolls a 1 and a 13, the halfling could use the Lucky trait to reroll the I.
Nice catch, I completely missed that. It's funny how you can become so familiar with the rules that you gloss over sections of the book you think you already know, then have to ask a question that is answered in that section. I mean, advantage and disadvantage is a pretty simple and intuitive mechanic, why would I ever go back and read that section once I know how it works? Given that Lucky is a very specific rule, while advantage and disadvantage are much more general rules, I'd never have thought to look there for information on Lucky.

Edit: What if you roll double 1s with disadvantage? If you only reroll one die, then the lowest result is still 1, unless that rerolled die superceeds both dice. This would, however, imply that in the example case of rolling a 1 and a 13 while you have advantage, that choosing to reroll the 1 means you also give up the 13. This is a statistically bad move, as you're more likely to roll lower than 13 than higher, although if a 13 was insufficient for success then it would still be a good idea to reroll.

[Coffee_Dragon]

Halfling Luck specifies that if you reroll a 1 you must take the rerolled value. That means if you rolled a 1 on either die you reroll the 1 and then take the rerolled value.

People can read this differently, of course, but I take the "use" in Lucky to mean "use for the result of this one roll of a die", i.e. the word "use" has no special mechanical meaning that obviates the rest of the context of the roll. So if with disadvantage you roll a 1 and a 13, then reroll the 1 into a 17, you "use" the 17 for the first roll, then "use" the 13 for the overall result per the instructions for disadvantage.

[NNescio]

This isn't specifically spelled out in the rules, and in at least one case is contradicted by the way that Sage Advice rewrote"clarified" the rules, but in all situations where there are multiple d20s being rolled from more than one special rule allowing dice substitution et al, I treat it as being done sequentially. The one exception I can think of is Elven Accuracy, which explicitly applies when and during an Advantage roll.

It is. PHB-p.173, under the Advantage and Disadvantage rules (so, about as primary as it can get). The Lucky trait was even called out as a specific example.

Text is as quoted by Lyracian, but here is a clearer-formatted version:


When you have advantage or disadvantage and something in the game, such as the halfling’s Lucky trait, lets you reroll the d20, you can reroll only one of the dice. You choose which one. For example, if a halfling has advantage on an ability check and rolls a 1 and a 13, the halfling could use the Lucky trait to reroll the 1.

—PHB-p.173

There's also the 2018 errata which clarifies the above rule:


[New] Advantage and Disadvantage (p. 173). In the first sentence of the fourth paragraph, both instances of “reroll” have been changed to “reroll or replace.”

— PH Errata (2018)-p.2

(To let it work on abilities that specify "replace" instead of "reroll", which is important from a strict RAW perspective.)

Applying the erratum:


When you have advantage or disadvantage and something in the game, such as the halfling's Lucky trait, lets you reroll or replace the d20, you can reroll or replace only one of the dice. You choose which one. For example, if a halfling has advantage or disadvantage on an ability check and rolls a 1 and a 13, the halfling could use the Lucky trait to reroll the 1.

The above is also the version found in 'reprints' (including official digital ones like D&D Beyond).

...So, a creature with the Lucky trait (not to be confused with the Lucky feat) may pick one of the Advantage/Disadvantage d20 rolls to reroll, provided it came up as 1. If both rolls came up as 1, then the Halfing (or whatever creature with the same trait) may only pick one of them (the RAW text in the Lucky trait seem to imply one can choose both, but the Advantage/Disadvantage rules overrules this and also provides a specific example).

(Yes, this makes it useless if both Disadvantage rolls come up as 1s.)


Halfling Luck specifies that if you reroll a 1 you must take the rerolled value. That means if you rolled a 1 on either die you reroll the 1 and then take the rerolled value.

It is... possible to read "use" that way, I suppose, but that's (IMHO) less intuitive (requires a more expansive reading of "use", as "use it as the final result"), and one would think they would have specified it that way in the Lucky example brought up in the Advantage and Disadvantage rules, if that was what they intended it to mean.




(Dis)Advantage gets applied first almost universally, because that's about the only one where you know you're rolling "extra" dice first. Then, you resolve the (dis)advantage, picking which of the d20s applies as your roll. Then, you evaluate whether, based on that die roll (which now is only one d20 result), whether you wish to apply (or can apply) other "reroll" or "extra die" mechanics. For example, if you have Halfling Luck and the final (dis)advantage result is a 1, you reroll the die. If you have Lucky and spend a luck point, you roll a new d20 and take either it or the one that you have settled on after resolving (dis)advantage.

The Lucky feat circumvents the above restriction because it lets you "roll an additional d20", and you get to "choose which of the d20s is used for the attack roll, ability check, or saving throw." So, with Advantage/Disadvantage one get to roll three d20s and choose which of the d20 to use. (That's part of why Lucky is powerful — it allows one to turn even Disadvantage into 'Super' Advantage. [caveat: it still counts as Disadvantage so things like Sneak Attack would still get blocked.])

As for how the Lucky feat would interact with the Lucky trait on Advantage/Disadvantage rolls... well, it is somewhat ambiguous but presumably the "only one of the dice" restriction only applies to the Advantage/Disadvantage pair.



I forget Portent's exact wording, but it replaces the entire roll, as well. So if you apply it before you roll, it doesn't matter whether the roll is at (dis)advantage or not; the Diviner foresaw the result and proclaims it. If you apply it after the roll, you apply it as the final result, regardless of how many dice were rolled to get there.

Portent specifies "you must choose to do so" (i.e. use the portent die) "before the roll".



This treatment is a little complicated to write out, but the execution is simple and straightforward, because you're never asking which die you reroll or replace: it's always only one die result being manipulated at a time.

I like how consistent your way works, but unfortunately this isn't RAW. (Which is a bunch of specific sui generis cases, as is most things in 5e.)

[Segev]

I'm aware of the various rulings people have given it before. This is why I acknowledged what I said wasn't spelled out in the rules. It's how I rule it, because it makes the most sense to me.

Now, limiting to rerolling/replacing only one of the dice makes some sense in some cirucmstances, fluff-wise, but those circumstances are only cases where it makes about as much sense as replacing the final result. Whereas situations where it fails to make sense (e.g. Portent) or makes things stupid ("Disadvantage? You mean SUPER Advantage!") only come up if you go with that version.

So my ruling on it, call it a house rule if for any reason (including you think "it totally is one!") that makes you feel better, is to replace or reroll the final die result at each step. Yes, it makes Halfling Luck and Portent more powerful on Disadvantage. But not egregiously so. And it prevents Luck from making Disadvantage something you'd actively seek out to get "super advantage" with your Luck point.

Honestly, I don't think it's TOO broken, and for the right character or the right game, the "Super Advantage" ruling might be fun as a quirk. I could totally build a character around that concept. But it's counterintuitive enough that most of the time I don't want to see it in my games. And my ruling makes for a simple principle to apply universally to all these situations with reasonable results.