How do the multiple attack rolls of Whirlwind Attack work with Lunging Attack's bonus to the attack's damage roll?

Question

At 11th level the Ranger subclass Hunter can get Whirlwind Attack:

You can use your action to make a melee attack against any number of creatures within 5 feet of you, with a separate attack roll for each target.

When this is combined with Lunging Attack maneuver from the Battle Master:

When you make a melee weapon attack on your turn, you can expend one superiority die to increase your reach for that attack by 5 feet. If you hit, you add the superiority die to the attack’s damage roll.

Does the extra damage apply across all damage rolls (I'm ignoring the range change, that much seems like it would make no difference as Whirlwind Attack fixes the range)?

Whirlwind Attack is odd in that it's one attack, as per Sage Advice Compendium (page 4):

Q. Can a ranger move between the attack rolls of the Whirlwind Attack feature?

A. No. Whirlwind Attack is unusual, in that it’s a single attack with multiple attack rolls. In most other instances, an attack has one attack roll. The rule on moving between attacks (PH, 190) lets you move between weapon attacks, not between the attack rolls of an exceptional feature like Whirlwind Attack.

The wording seems off, but I can't see any other reason to allow it? Every other maneuver used with an attack triggers on a hit or a roll, so this seems like a deliberate exception?

Answer 1

Whirlwind Attack's range does not depend on your reach

Whirlwind Attack says you can target "any number of creatures within 5 feet of you". It doesn't matter what the reach of your normal attacks is. You could be a bugbear wielding a halberd and using Lunging Attack, but Whirlwind Attack is still limited to targets within 5 feet of you.

The reasoning for this is obvious: if Whirlwind Attack worked based on the reach of your normal attacks, the number of potential targets would increase quadratically as your reach increases, which is a recipe for unbalanced combinations. Limiting the range to 5 feet also makes sense thematically: you are attacking everything around you in all directions, not reaching out in any specific direction.

Lunging Attack can add the superiority die to a damage roll

Just because Whirlwind Attack doesn't care about your weapon's reach doesn't mean you can't use Lunging Attack with it. If you do so, it increases your reach, which Whirlwind Attack then ignores. But then you still get to add the superiority die one of the damage rolls, because that is part of the maneuver's effect.

I say one of the damage rolls because the rules for making an attack say to roll damage on a hit. Hence, if an attack hits multiple targets, you roll damage separately for each hit. As for how Lunging Attack's damage bonus interacts with this, the exact wording is:

[...] If you hit, you add the superiority die to the attack’s damage roll.

The ability is obviously written for what is by far the most common case: an attack with a single damage roll. It doesn't specify how to generalize this to the much rarer case of an attack with multiple damage rolls, so it's ultimately the DM's call how to apply it. However, rolls are rarely, if ever, used more than once, so the most likely intent is that the superiority die is added to one damage roll and then discarded. Still, a generous DM might allow you to add the bonus to the damage for every hit.

You should probably use another maneuver if you can

Note that many other maneuvers also add your superiority die to the damage roll and potentially have other useful effects as well, so you will most likely be better off using one of those with Whirlwind Attack instead of Lunging Attack. (Exactly how each of those manuevers interact with Whirlwind Attack is beyond the scope of this question.)

Answer 2

By the wording in the book, lunging attack would only add a superiority die to the damage of one of multiple attacks and have no other effect.

That wording seems pretty clear to me - you make an attack (not an action to attack that would gain Extra Attack and etc, just a regular, single ol' attack) against any number of creatures within 5'. If there's like 50 tiny fey flying around stabbing you, you can probably attack all of them if they count as separate guys and not like, a Swarm. More reasonably, if say 4 goblins are all standing next to you trying to stab you with shortswords, you may make an attack against each of them - rolling 4 times to hit, and if you hit, rolling damage. An attack, aka 1 attack, each, against any number of enemies - within 5'.

This sage advice thing though has a wildly different interpretation of what these words mean. It seems wildly out of line with how the rest of 5e works, and specifically aimed at 'stopping someone moving while using whirlwind attack' by defining it to be a different thing than weapon attacks (which is weird, because you're making... attacks... with a... weapon).

Effectively the author clearly did not want people to be move and get to attack potentially everyone within their movement line with whirlwind attack, and made up some reasons as to why. This made a further problem for them down the line (this is now a weird single-attack-multiple-roll-multiple-target ability that interacts oddly with things like superiority dice and potentially other abilities that add damage to a single 'attack' or add to-hit to a single 'attack') that a simple 'no you can't, it's enemies within 5' of the position you are in when you use the ability, you can move between the attacks but this does not grant you additional attacks' would not have.

Regardless, if Sage Advice is taken as rules text, then quite explicitly, you add that superiority dice to ALL damage rolls made as a result of whirlwind attack. It's ONE ATTACK, and lunging attack says that you add range to your attack (pointless - whirlwind specifies within 5') and then if that attack does damage, you add the superiority die to the damage. And since it's all part of that one attack according to sage advice, bam. Your d8 (or w/e) gets added to everything. And potentially other stuff too, i'd have to check the wording on things like Divine Smite etc.

Now like, is this broken?

I mean, probably not? At level 11, a Wizard can douse a room in flames and turn like twenty guys into charcoal briquettes 10+ times a day. Being able to attack some guys standing next to each other and get some damage bonuses to that if you've like, taken a feat or multiclassed, does not seem amazing comparatively. If you could do it at level 3, and by level 7 you'd have 3 abilities all adding damage dice to that massive swirly-boi swing then sure. That sounds okay. Not great, just sorta Fireball-ish. But 11 levels in ranger to get whirlwind attack in the first place means it's unlikely to be all that exciting.

In fact it is likely to be very very underwhelming.

Is this the designer's intent?

Did they want you to get all possible bonuses on whirlwind attack to make that 1 attack you do to each guy very deadly?

Unlikely. 5e is designed (and sage adviced, the new term for 'errata') in a fairly reductive and anti-optimization manner. Anything like this ('comboing' abilities) seems to be viewed with a combination of disdain and deep alarm.

It's likely that the designers think attacking three adjacent bog trolls (or whatever) for weapon damage + stat is a perfectly good and valid use of a level 11 ranger's turn, and that doing more than that would be too strong.