How can we determine what a 'magical effect' is?

[Specter]

Spell Resistance (the Abjurer feature) says:
"Starting at 14th level, you have advantage on saving throws against spells. Furthermore, you have resistance against the damage of spells."

Circle of Power (Paladin spell) says:
"Divine energy radiates from you, distorting and diffusing magical energy within 30 feet of you. Until the spell ends, the sphere moves with you, centered on you. For the duration, each friendly creature in the area (including you) has advantage on saving throws against spells and other magical effects."

It's clear that a 'spell' and a 'magical effect' are distinct. And then, I realized I couldn't tell if a dragon's breath belongs in the latter; is the breath purely a physico-chemical reaction (like a lighter or a pesticide spray), in which case Circle of Power doesn't help? Or is it conjured mystically somehow? We can ask similar questions about a banshee's wail or a ghoul's touch, for example.

So how can we say for sure what a 'magical effect' is? Am I missing something RAW?

[Unoriginal]

Spell Resistance (the Abjurer feature) says:
"Starting at 14th level, you have advantage on saving throws against spells. Furthermore, you have resistance against the damage of spells."

Circle of Power (Paladin spell) says:
"Divine energy radiates from you, distorting and diffusing magical energy within 30 feet of you. Until the spell ends, the sphere moves with you, centered on you. For the duration, each friendly creature in the area (including you) has advantage on saving throws against spells and other magical effects."

It's clear that a 'spell' and a 'magical effect' are distinct. And then, I realized I couldn't tell if a dragon's breath belongs in the latter; is the breath purely a physico-chemical reaction (like a lighter or a pesticide spray), in which case Circle of Power doesn't help? Or is it conjured mystically somehow? We can ask similar questions about a banshee's wail or a ghoul's touch, for example.

So how can we say for sure what a 'magical effect' is? Am I missing something RAW?



Is the breath weapon of a dragon magical?
If you cast antimagic field, don armor of invulnerability, or use another feature of the game that protects against magical or nonmagical effects, you might ask yourself, “Will this protect me against a dragon’s breath?” The breath weapon of a typical dragon isn’t considered magical, so antimagic field won’t help you but armor of invulnerability will.

You might be thinking, “Dragons seem pretty magical to me.” And yes, they are extraordinary! Their description
even says they’re magical. But our game makes a distinction between two types of magic:

• the background magic that is part of the D&D
multiverse’s physics and the physiology of many
D&D creatures
• the concentrated magical energy that is contained in a
magic item or channeled to create a spell or other focused
magical effect

In D&D, the first type of magic is part of nature. It is no more dispellable than the wind. A monster like a dragon
exists because of that magic-enhanced nature. The second type of magic is what the rules are concerned about. When
a rule refers to something being magical, it’s referring to that second type. Determining whether a game feature is magical is straightforward. Ask yourself these questions about the feature:

• Is it a magic item?
• Is it a spell? Or does it let you create the effects of a spell
that’s mentioned in its description?
• Is it a spell attack?
• Is it fueled by the use of spell slots?
• Does its description say it’s magical?

If your answer to any of those questions is yes, the feature is magical.

Let’s look at a white dragon’s Cold Breath and ask ourselves those questions. First, Cold Breath isn’t a magic item. Second, its description mentions no spell. Third, it’s not a spell attack. Fourth, the word “magical” appears nowhere in its description. Our conclusion: Cold Breath is not considered a magical game effect, even though we know that dragons are amazing, supernatural beings.


https://media.wizards.com/2017/dnd/downloads/SA-Compendium.pdf

Here you go, Specter.

[Specter]

Hey, thanks!