How do you determine a druid's eligibility to use Elven Accuracy's reroll while in Wild Shape (assuming they do have advantage)?

Question

Consider a druid who has the Elven Accuracy racial feat (available to Elves and Half-Elves). Among other things, this feat says:

Whenever you have advantage on an attack roll using Dexterity, Intelligence, Wisdom, or Charisma, you can reroll one of the dice once. [XGtE, pg. 74]

As discussed here, when in Wild Shape:

You retain the benefit of any features from your class, race, or other source and can use them if the new form is physically capable of doing so. [PHB, pg. 67]

Because of this, Elven Accuracy should apply to any attacks made while in Wild Shape.

However, beasts' stat blocks don't explicitly say which ability is being used in an attack. For example, the Wolf's bite attack simply says it's +4 to hit and does 2d4+2 piercing damage.

Now, it may be possible to deduce which ability was used. In the case of the Wolf, from a +2 damage bonus, we can guess that that relevant ability score modifier is equal to that bonus (+2). This would be consistent with +4 to hit if the wolf has a proficiency bonus of +2 (since +2+2=+4), which it does (according to its stat block). As a mundane attack, the Wolf must have used Strength or Dexterity, but the Wolf's Strength is only +1 while its Dexterity is +2. Therefore the Wolf used Dexterity.

In contrast, a similar line of reasoning with the Dire Wolf leads to the conclusion that it uses Strength to power its bite attack.

So a druid in Wolf shape should be able to apply Elven Accuracy, but a druid in Dire Wolf shape should not.

Is this the correct way to determine a druid's eligibility to use Elven Accuracy's reroll while in Wild Shape?

It seems awfully convoluted.

Answer 1

Melee attacks use strength by default, but sometimes smaller monsters use dexterity.

The rules for attack rolls state:

Ability Modifier. The ability modifier used for a melee weapon attack is Strength, and the ability modifier used for a ranged weapon attack is Dexterity. Weapons that have the finesse or thrown property break this rule.

But, we see in the Dungeon Master’s Guide:

When a monster has an action that requires an attack roll, its attack bonus is equal to its proficiency bonus + its Strength or Dexterity modifier. A monster usually applies its Strength modifier to melee attacks, and its Dexterity modifier to ranged attacks, although smaller monsters sometimes use Dexterity for both.

So if you have a melee attack, the ability modifier is assumed to be strength unless it’s not. Great system, I know. So your intuition to reverse engineer the bonus based on attribute scores is probably the best approach here. In the case of the wolf, the calculations indicate that we are using dexterity.

And sometimes the bonuses make no sense at all.

That said, as Eddymage states in a comment, even our method of calculating backwards to determine which attribute is used can fail:

There is quite a number of incrongruences in monsters' attack bonuses. See the quasit for example: the proficiency bonus is +2, its STR is 5(-3) and its DEX is 16(+3), but it has a +4 to hit and the damage is 1d4+3.

So generally, you should be able to figure out which attribute is used if the modifiers are different, but sometimes you will just have to ask your DM.

To further complicate things, we have this question from the Sage Advice Compendium:

The bite attacks of ghouls and ghasts don’t appear to have proficiency bonus added in. Intentional or mistake?

Intentional; it’s a ghoul/ghast thing. They’re exceptionally bad at biting, compared to their claw attacks. Monsters sometimes have stat quirks like that.

So just talk to your DM about it if the usual rules don't add up.

Answer 2

I think instead of looking to the monster attributes you should try to figure out what makes sense for each creature (with confirmation from your DM). The attribute bonuses can help of course but they don't need to be the end of it.

As Thomas Markov's answer points out, sometimes the monster's damage bonuses doesn't line up with their attributes:

There is quite a number of incrongruences in monsters' attack bonuses. See the quasit for example: the proficiency bonus is +2, its STR is 5(-3) and its DEX is 16(+3), but it has a +4 to hit and the damage is 1d4+3.

We can still assume a Quasit is using Dex, since they are fast and nimble creatures, and the bonus is much closer to the one of that stat. That's why it's reasonable to use yours and your DM's intuition for this matters.

You mention how for the Wolf and Dire Wolf, judging from the attributes, you'd conclude that the Wolf's attack is Dex and the Dire Wolf's is Str. This makes sense, each are using thier highest stat to attack.

However, a Dire Wolf can still be an agile creature or at least it can be portrayed that way. It has a Dex score of 15(+2) and a Str score of 17(+3) so the difference isn't that large. Moreover, Wolves and Dire Wolves are usually used in the same encounter (e.g: 2 Dire Wolves and 4 Wolves), which gives the idea they can be part of a pack, meaning the Dire Wolves could just be grown out Wolves (again, this depends on the DM). As such, a Dire Wolf may be attacking the same way it was when younger and just gets its +2 upgraded to a +3 for its shear size. So it may still be relying on it's ability to quickly go in and bite rather than it's now improved brute strenght.

That's a long explanation but what I'm trying to get at is that it seems reasonable that a Dire Wolf uses Dex, stats aside. Wolves are agile, a larger wolf can be agile too.

Now, your DM could say that they see Dire Wolves as taking advanteage of their size and the strength it gives them to power their attacks and that's reasonable too.

I'm saying that using your intuition and what you know about these creatures can be the best and quickest way to get out of this doubt. It's the kind of thing DM's have to make a ruling about all the time. Say one of the players gets ahold of a weapon type not in the DMG, you'll expect to be asked "can this use Dex or Str?", I see it as in the same vein as "Does the Giant Ape use Strenght for its attacks?" (personal asnwer is yes, definitely).

Also, you'll likely use the same animals multiple times, it's not like you always turn into something different so it's not somethng you'll be asking about every session.