Is there a distinction between magical damage and nonmagical damage?

Question

At various times while using this site, I've seen assertions that damage cannot be magical or nonmagical, and that referring to "magical damage" or "nonmagical damage" is thus nonsense. For example, damage from the fireball spell and damage from a flask of alchemist's fire are both just "fire damage" not "magical fire damage" and "nonmagical fire damage".

However, I've also seen some people assuming the opposite, such as this question. Such an assumption might arise from the numerous other ways that "magical" versions of effects are treated differently from "nonmagical" versions, such as the pyrotechnics spell which only works on "nonmagical flame".

Does it make sense to talk about whether damage is magical or not?

Answer 1

A distinction exists

In the rules on damage resistance, the following example is given:

Multiple instances of resistance or vulnerability that affect the same damage type count as only one instance. For example, if a creature has resistance to fire damage as well as resistance to all nonmagical damage, the damage of a nonmagical fire is reduced by half against the creature, not reduced by three-quarters.

First of all, this example gives evidence that "resistance to all nonmagical damage" is a valid type of damage resistance, and that the phrase "nonmagical damage" is itself a distinct category of damage (presumably defined as "damage that is not magical"). Additionally, because the example is being used to demonstrate that multiple applicable resistances do not stack, we can conclude that "resistance to all nonmagical damage" would grant resistance to damage caused by a nonmagical fire. If it granted resistance to damage caused by a magical fire as well, then the example wouldn't need to specify that the fire in question was nonmagical, thus I assert that "damage caused by a nonmagical fire" can be called "nonmagical fire damage" and "damage caused by a magical fire" can be called "magical fire damage".

Is "magical" a damage type?

"Magical" is not a damage type. The rules on damage types are short, in fact they mostly say "Damage types have no rules of their own", but they include a list of all the damage types and "magical" is not one of them. If you look through all the books you will not find an effect which simply "deals magical damage". It never exists in isolation because it is not a damage type.

What is "magical damage" if it is not a damage type?

"Magical" is a modifier that can be applied to damage, just like it can be applied to almost anything else. Fire created by magic is "magical flames". Darkness created by magic is "magical darkness". In the same way, damage caused by magic is "magical damage" even though "magical" is not a damage type and the damage also has a type that isn't "magical".

As an example lets take a +1 longsword. Nonmagical longswords deal slashing damage. Magical longswords also deal slashing damage. However, Nonmagical longswords deal nonmagical slashing damage while magical longswords deal magical slashing damage. Thus, a +1 longsword deals magical damage.

Maybe the example in the Damage Resistance rules is a mistake?

Although I can find no references directly to "magical damage", there are several cases of resistance to "nonmagical damage" or a subset of it, and which do not use the "damage from nonmagical attacks" phrasing. From things listed in the Basic rules, the spell gaseous form grants "resistance to nonmagical damage", the spell stoneskin grants "resistance to nonmagical bludgeoning, piercing, and slashing damage", and the magic item armor of invulnerability grants "resistance to nonmagical damage". Looking outside the Basic Rules, Demon Lords from Mordenkainen's Tome of Foes, such as the Demogorgon on page 144, have Damage Immunity to "bludgeoning, piercing, and slashing that is nonmagical." I find it unlikely that all of these are mistakes.

Maybe it means something else?

The most authoritative source available for how to determine whether an effect is magical comes from the question "Is the breath weapon of a dragon magical?" answered in the Sage Advice Compendium. There is a lot of information there, but the most relevant part is this sentence:

The breath weapon of a typical dragon isn’t considered magical, so antimagic field won’t help you but armor of invulnerability will.

Thus armor of invulnerability is used as the canonical example for "protecting you from damage caused by a nonmagical effect". I'm not sure how much clearer it could be.

In conclusion

The phrase "nonmagical damage" is officially used in multiple places to mean "damage caused by an effect/feature/item that is not magical", using the typical definition of "magical". To complement that, the phrase "magical damage" would sensibly mean "damage caused by an effect/feature/item that is magical", though I haven't found that phrase used anywhere. Thus it is sensible to talk about "resistance to nonmagical damage", and "ways to cause nonmagical damage".

Answer 2

It is the source of the damage, not the damage itself, which is magical or non-magical. Fire Resistance applies to damage whose source is fire, not to some mystical 'fire-ness' of the damage itself. Similarly, magical is a type of damage source, not a type of actual damage. Fireball does damage, sourced from fire, also sourced from magic. So magic resistance and fire resistance both help you; however, if you sat on a torch, only your fire resistance would help. If damage itself had the attributes of its source, you could get insane things like 'Cure fire damage' effects that only give you back the hit points lost to fire.

Similarly for piercing, slashing, or bludgeoning. These describe the sources, not the actual damage itself, it's just a shorthand to discuss 'piercing damage' (We use hit points as an abstraction, in real life, a poiniard's puncture wound and a scimitar's slashing wound are different, but in DnD, all damage is abstracted to undifferentiated 'Hit Points' so such distinctions don't matter in play after the damage is done.)

Answer 3

There is a list

The following questions can be asked to determine if something is magical, for the purposes of mechanics like resistance and vulnerability. Citation: Is the breath weapon of a dragon magical?

Is it a magic item?

E.g. A magic sword deals magical slashing/piercing damage.

Is it a spell?

E.g. Fireball deals magical fire damage.

Is it a spell attack?

E.g. A Flameskull's Fire Ray action deals magical fire damage. (Spell attacks not attached to a specific spell are typically found on monsters, not PC abilities.)

Is it fueled by spell slots?

E.g. A paladin's Divine Smite feature deals magical radiant damage.

Does its description say it's magical?

E.g. A beholder's Eye Ray feature deals magical damage, if any.

If the answer to all those questions is "No," then the damage is nonmagical.