Does Nondetection plus Invisibility hide you from the The Third Eye Wizard ability?

Question

Nondetection protects you from divination magic.

In an early post on Sage Advice, I read Nondetection + Invisibility even protects against True Seeing. Okay, makes sense.

But what about the Divination Wizard's Third Eye ability? It doesn't read that you cast a spell or in particular that you are using magic on yourself. It only mentions that you use an action and increase your powers of perception. As such, there's no magic involved, correct? And as such these powers could perceive through invisibility + nondetection?

It would make sense to treat it as magical, but at the same time I've always wondered why the sight ranges seemed severely limited compared to their spell-based counterparts. Perhaps this is why? Hoping for answers based on RAW only or Mike Mearls/Jeremy Crawford posts. (Links please.)

Answer 1

Nondetection will hide you from The Third Eye

See this related question: Do Nondetection and Invisibility protect you from True Seeing?

Furthermore, see the following Sage Advice: Does Nondetection plus Invisibility beat True Seeing?

I'll summarize some key points in the other answer:

• There are only two Divination-type spells that create magical scrying sensors: Clairvoyance and Scrying -- these are covered in part 2 of the Nondetection spell
• Only True Strike and Hunter's Mark are the only two divination spells that ask you to target a creature. Both of these are not "detect-class" spells -- that is, they don't find something in the way you would think Nondetection wants to hide you
• Most other Divination-type spells target the caster (range of Self) such as See Invisibility, Detect Thoughts, or True Seeing
• It is absurd that Nondetection, a second-level spell, protects against only one cantrip, and one 1st level spell. Therefore:
• A better interpretation is: Nondetection prevents you from being detected by any divination magic.

Again, refer to the Sage Advice linked above if you find this objectionable. It is more of a spirit of the law argument than a letter of the law one.

Answer 2

While a bit old and against the older answer.

Nondetection will not prevent you from seeing someone that is invisible, should you be using the Third Eye. Both of the examples in the other answer, while good for the time, are for spells and magic. I suggest taking a look over at my answer and question over here for more info on the matter.

This has to do with what magic is, I advise you to read the SA Compendium but the gist has to do with what classifies an act of magic as magic. I emphasized the main portion of why this is.

• 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?

The see invisible ability of Third Eye does not mention using the effects of the spell 'See Invisible' and because it does not explicitly mention using the spell, as with my example for Tranquility on my linked answer and question, it is not considered a spell, or magical effect.

Because it is not considered a spell or magical effect it is not considered divination. Which leads us back to the beginning... Nondetection will not prevent you from seeing someone that is invisible..., should you be using the Third Eye.