What part of a multi-type damage roll is reduced by a non-type-specific effect?

Question

Effects like Cutting Words (PHB, p. 54) and Spirit Shield (XGtE, p. 10) reduce damage by a roll, irrespective of damage type (PHB 196). However, single damage rolls can have multiple damage types, as confirmed (for wording) by Jeremy Crawford in this tweet.

How do you know which part of the damage is reduced?

This could actually make a difference to the amount of damage taken if, for example, the creature taking damage is resistant to one or more of the damage types involved.

Cutting Words: ... When a creature that you can see within 60 feet of you makes an attack roll, an ability check, or a damage roll, you can use your reaction to expend one of your uses of Bardic Inspiration, rolling a Bardic Inspiration die and subtracting the number rolled from the creature's roll.

Using this ability to expand upon the examples found in this related question and this other related answer:

Barny, an Ice Devil (MM, p. 75) hits Bobby, rolling 9 slashing damage and 11 cold damage.

Bobby's ally, Vera, is a level 10 bard of the college of Lore, and uses her Cutting Words ability on the attack's damage roll. She rolls a 9, which is subtracted from the Barny's damage roll.

Bobby is wearing his Boots of the Winterlands (DMG, p. 156), giving him resistance to cold.

We know that "resistance and then vulnerability are applied after all other modifiers to damage" (PHB, p. 197) and both slashing damage and cold damage are treated as "one big damage roll" (see the JC tweet), so is all the 9 slashing damage removed by cutting words, and then the cold damage halved for 5 total damage, or is 9 of the cold damage removed by cutting words, leaving 2 to be halved for a total of 1 + 9 = 10 damage taken by Bobby?

Who makes this decision?

When an effect (like cutting words) reduces damage without specifying type from a source containing multiple damage types, what part of the damage is reduced?

Answer 1

The Bard decides, but it is somewhat table dependent

As you've quoted for cutting words, the mechanic states:

When a creature that you can see within 60 feet of you...a damage roll, you can use your reaction to expend one of your uses of Bardic Inspiration, rolling a Bardic Inspiration die and subtracting the number rolled from the creature's roll.

When damage is being rolled, each type is rolled separately: different die, different modifiers, different functional rolls (but still counts as One Big Roll with regard to damage.)

The bard is seeing the damage coming in and using their mechanic to reduce the damage they want to reduce.

Other tables may differ

However, there is no written rule on this and a DM could easily say it was their decision. But I'd suggest to let the Bard bard and choose when and how they want to apply their mechanic.

But you have to pick one from somewhere in some circumstances (but not all)

Due to issues regarding resistance, vulnerability, there needs to be a mechanic where you choose which damage type to Cut. If there are none of the mechanics in play, then it doesn't matter - but if there are, you need to separate out the types otherwise you have no way to determine how and where to cut the damage.

Crossover damage

In the cases where the damage reduction is greater than any single damage type's value, then the remaining reduction would cross over to the other damage type. The bard has targeted Damage Type A, and the remainder (if any) goes to Damage Type B.

Answer 2

Cutting Words subtracts from the Total Damage and not the components

JC's tweet reads as follows:

When something in the game (Sneak Attack, Divine Smite, hex, etc.) causes your attack/spell/etc. to deal extra dice of damage, those dice are added to the damage the effect is already dealing, if any. It's one big damage roll, extra damage included.

Essentially, JC is saying that the result of a damage roll with any extra die added on is the sum of the components of damage, explicitly including multiple damage types in the tweet, as it refers to Hex and Divine Smite. These effects add Necrotic or Radiant damage, respectively, to attacks, regardless of what the original damage type was.

Divine Smite, for example, reads:

Starting at 2nd level, when you hit a creature with a melee weapon attack, you can expend one spell slot to deal radiant damage to the target, in addition to the weapon’s damage. The extra damage is 2d8 for a 1st-level spell slot, plus 1d8 for each spell level higher than 1st, to a maximum of 5d8. The damage increases by 1d8 if the target is an undead or a fiend, to a maximum of 6d8.

By the ruling of the JC tweet, then, this would all be determined as "One big Damage Roll", or the sum of the damage type delivered by the melee weapon and the Radiant Damage, even though these types of damage are often different. And if we go back and look at the Cutting Words description:

...subtracting the number rolled from the creature's roll.

We see the damage roll from the creature is singular, not plural, which would reference the single "One big Roll" from the JC tweet. Thus, the Specific Rules of Cutting Words allow it to bypass the normal rules of Damage Vulnerability and Resistance being applied after all other modifiers, as Cutting Words specifically applies to the damage total and not the components of damage.

Therefore, the way this would work-out on the table would be:

1. Barry rolls to hit Bobby. Success
2. Barry rolls each damage value, 9 Slashing and 11 Cold Damage
3. Bobby does not have Resistance nor Vulnerability to Slashing Damage, so that damage stays the same.
4. Bobby does not have Vulnerability to Cold Damage, but he does have Resistance. He resists half of that damage rounding up, which means the Cold Damage component of the Total Damage is halved rounding down.
5. This damage adds together into the total Damage, the Damage Roll
6. Cutting Words, a specific spell, then applies its Damage Reduction to the result of the Damage Roll

It is possible to make a mathematical formula out of this:

$$D = [\frac{(1+v_{1})*d_{1}}{(1+r_{1})}+\frac{(1+v_{2})*d_{2}}{(1+r_{2})}]-S$$

• \$D\$ = Damage
• \$S\$ = Damage Subtraction
• \$d_{1}\$ = Damage component 1
• \$d_{2}\$ = Damage component 2
• \$d_{n}\$ = Any given Damage Component, for use in the following:
• \$r_{n}\$ is a Boolean value representing the existence of resistance relative to \$d_{n}\$, 0 for False, and 1 for True
• \$v_{n}\$ is a Boolean Value representing the existence of a vulnerability relative to \$d_{n}\$, 0 for False and 1 for True

Of course, you can add further types as much as you need, so long as you follow the basic formula for each individual type of damage:

$$[\frac{(1+v_{n})*d_{n}}{(1+r_{n})}]$$

Answer 3

Cutting Words applies after resistance because it is not damage reduction, it is subtraction with unique and explicit behaviour.

Consider the text of Cutting Words:

When a creature that you can see within 60 feet of you makes an attack roll, an ability check, or a damage roll, you can use your reaction to expend one of your uses of Bardic Inspiration, rolling a Bardic Inspiration die and subtracting the number rolled from the creature’s roll. You can choose to use this feature after the creature makes its roll, but before the DM determines whether the attack roll or ability check succeeds or fails, or before the creature deals its damage.

The term subtract is incredibly rare in DnD5e. It is used 9 times in the entire basic rules. It is only ever used when referring to the mathematical operation;

• "For disadvantage, subtract 5 [from a passive skill check]"
• "To determine an ability modifier without consulting the table, subtract 10 from the ability score and then divide the result by 2 (round down)"
• "Whenever a creature takes damage, that damage is subtracted from its hit points.", etc.

The term "subtract" should not be understood as the gameplay mechanic reduce damage.

With all other uses of the feature the subtraction happens "before the DM determines whether the [roll] succeeds or fails". This is after all modifications and other effects have been applied, right before the DM resolves the roll.

I will argue that this same intent--"before the DM resolves the roll"--also applies to damage rolls which is why they chose the unique term "subtracting" to distance it from existing mechanics and prevent confusion. The timing of the skill, "before the creature deals its damage", is explicitly mentioned. This is unusual because if this was a normal 'damage reduction' then the timing is already defined in the Combat rules, and this is not where it would happen. Normal 'damage reduction' happens "before resistance and weakness is applied".

What exactly does "deals its damage" mean? This isn't a normal choice of words. This phrase is used in a lot of contexts but it's not really clear to me. "Swords deal slashing damage", "an attack deals 5 damage".

The rules for Object Armor Class provides a hint:

An object's Armor Class is a measure of how difficult it is to deal damage to the object when striking it (because the object has no chance of dodging out of the way).

This suggests "dealing damage" does not mean rolling AC, which is a start.

Knocking A Creature Out says:

When an attacker reduces a creature to 0 hit points with a melee attack, the attacker can knock the creature out. The attacker can make this choice the instant the damage is dealt.

This seems to say that "damage is dealt" is when the damage is applied. That is to say, after rolling damage you can choose to knock the creature out, you don't do it before rolling damage.

In most circumstances resistances are the last thing to be resolved. However, the specific overrules the general, and the text "before the creature deals its damage" can be interpreted as "directly before the creature deals (ie reduces the hp of the target) its damage". As opposed to if the text read "after damage is rolled".

In the rules for Making An Attack:

1. Choose a target. Pick a target within your attack's range: a creature, an object, or a location.

2. Determine modifiers. The DM determines whether the target has cover and whether you have advantage or disadvantage against the target. In addition, spells, special abilities, and other effects can apply penalties or bonuses to your attack roll.

3. Resolve the attack. You make the attack roll. On a hit, you roll damage, unless the particular attack has rules that specify otherwise. Some attacks cause special effects in addition to or instead of damage.

The DM deals the damage at the end of step 3, after all resistance and reduction is applied. Cutting Words is a special case subtraction that does not follow the normal rules, which is why it has special, unique wording. It is intended to modify the damage roll directly before Step 3.

This is just one reading, but it would resolve the question of "can I pick what type of damage to reduce". It also resolves associated questions like "does the troll regenerate", and a host of other small problems with picking or not picking what damage type you want to reduce.

Some caveats:

• While this answer is RAW, there is an assumption that the designers decided to use the word "subtraction" for a specific reason, and that they chose to explain the mechanics because they are abnormal. It is possible that the designers simply chose the word "subtraction" offhand. However I find it more useful to assume the designers are intentional with their language.
• Sometimes skills do repeat core mechanics, and it's possible the designer intended the description to be a general overview not actual mechanics, or they accidentally included mechanics from an older test version and it just slipped through the cracks and made it to publishing. I don't think this is a good argument as it brings all rules into question.
• Spirit Shield doesn't use this language, and so it is another issue entirely.
• There is apparently some debate as to whether "taking damage" and "being dealt damage" are the same thing. I think they are, and I have included arguments in support of this above.

In the comments Medix2 asked: "if an attack does, say, fire and cold damage, which ones are reduced by Cutting Words?" The answer is that Cutting Words subtracts from the damage roll, not from any specific type. Follow the steps as above;

1. Roll the die
2. Apply all modifiers
3. Apply all resistances or weaknesses You can now subtract the number rolled from the creature's attack. At this point the rules run out, all damage is assumed to be amalgamated and subtracted from the creature's health. Cutting Words is a special case that is not clearly covered by the rules.

This is important in the case of a Troll, it can only regenerate if not dealt fire/acid damage.

Your choices are: - Let the DM decide what damage has/has not been dealt (rule in favor of the monster) - Let the Bard decide what damage has/has not been subtracted (rule in favor of the players) - Ignore the question and have all damage types that get to this stage be 'dealt' but accept that it is possible they are 0 damage (unless the total damage is reduced to 0, then it would be reasonable to say that the creature takes no damage of any type). - Some other option, again this is not covered by the rules so pick whatever you think makes sense or makes the narrative interesting.