Advantage on saves vs. magical effects?

[Degwerks]

What exactly qualifies as Magical Effects?
For the example having advantage on saves versus spells and magical effects from a Holy Avenger? I know spells qualify.

Would the fear aura of outer planar creatures be a magical effect? Would it basically be only something that a creature has to use an Action of sorts to do?

[Dalebert]

Up to the DM ultimately but here's some thoughts from the rules designer.

Scroll down to where it says "Is a dragon's breath weapon magical." (Spoiler alert: it's not)
http://dnd.wizards.com/articles/features/rules-answers-february-2016

The basic checklist:
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?
Does its description say it’s magical?

*emphasis mine
I emphasized it because, for example, there are a number of ways to become invisible. While there is an invisibility spell, these should not be considered magical unless they specifically mention the spell.

Also the same notion apparently applies to Ki. Even though the lore describes it as magical in nature, monk abilities are apparently not considered magical for these purposes (https://www.sageadvice.eu/2016/05/11/does-stunning-strike-is-not-a-magical-effect-for-magic-resistance/) unless the specific ability checks off something in the list above. An example of a monk ability that would are the spells a shadow monk can cast using ki at 3rd level since they specifically mention those spells. You are in fact just casting spells but with ki instead of spell slots.


Would the fear aura of outer planar creatures be a magical effect? Would it basically be only something that a creature has to use an Action of sorts to do?

1) It's not a magic item.
2) It's not a spell but does it specifically mention something like "as per the fear spell"?.
3) I'm fairly certain it doesn't mention a spell attack; prolly a saving throw.
4) Does it's description say it's magical?