Quote from Jiyoad >>

Truesight allowing you to see into the ethereal plane suggests that you may see the soul of the thing you are looking at. So even if the physique of the thing was changed, it couldn't beguile it's true nature to you regardless while you are under the effects of this spell.

 
There's nothing to suggest that the soul of living creatures reside in the ethereal plane, they're implied to be on the same plane as their physical being. It's in their body. 

If not the soul, don't things have an astral body / aura that is visible from the ethereal plane?

Also, if the quote for [truesight] above is right is says: "automatically detect visual illusions" not just magic ones. So aren't stuff like sleight of hand and other tricks like makeup also illusions? And with the mention of shapechanger and magic transformation separately, then add in ethereal plane?

With all that, I would say it is fairly clear you aren't supposed to be getting around it without an artefact or something to counter truesight. Maybe there was something wrong with the mushrooms used in the spell? :D

I'd probably make it third level. Its like having near-true sight. Though I think it would be funny for someone with this spell to squint and lean in to a magical statue, only to find out it is an actual lion under the illusion of a statue that they just shoved their face into haha.

Quote from jmnc2 >>

So aren't stuff like sleight of hand and other tricks like makeup also {visual} illusions? 

{edit by PZ}

Yup!

Quote from Blue0440 >>

Quote from Babhdial >>

There's been some interpretation that a changeling's reshaping is physical rather than magical so that it might not work against that, nor against makeup

 Regardless, even if it is a physical transformation, Truesight allows you to "perceive the original form of a shapechanger," so it will work on Changelings. It will not, however, allow you to see through a disguise depending on makeup and clothes, since those simply cover up physical features, without changing them. 

 yeah no, its been clarified that a changelings shapechange is not see throughable with truesight, as when they shapechange that is their "original" form that is changing, its not some new form, they are changing who they are

I have created a ritual to give someone this ability once per day, that includes some rare materials + sacrificing one's eye in the process

Illusion is magic. Optical illusions may be a differente matter but Illusion is magic. Sleight of hand is a missdirection at best, a trick.

The spell says that you can see into the Ethereal Plane, so are you also able to see out of the Ethereal Plane?

Quote from The_Treebeard >>

I'm realizing now that having truesight and not darkvision is similar to having a Warlock's Devil's Sight and darkvision:

You can see through magical and normal darkness, but still suffer disadvantage to Wisdom (Perception) checks made in dim light. Obviously there are a lot of other benefits to True Seeing and truesight, but dim light is not one of them. This could explain why some monsters have both darkvision AND truesight.

 Yep this is one of the lesser known negatives of truesight. It's funny when monsters are given just truesight and more powerful versions of monsters often lose darkvision and blindsight when they get to that stage (greatwyrms being an example).

They end up being able to see worse in dim light and (in the case of creatures that lose blindsight) also can no longer see in fog and other non-darkness obscurement.

among us in real life?

Quote from ProphetZarquon >>

Quote from BekahY >>

1ft of truesight seems super useless to me. You'd have to get right up in somebody's face to see through any illusion or shape-shifting. I'd say you need at least 5 or 10 feet.

 Wait, for combat? Yes, mostly useless.

You really can't think of a use for it, outside combat, though??? Not useful at all? Interrogations, traps, magic items, illusions grand & small; but there's no usefulness to Truesight with less than 5ft of range? 

Hm. I feel like there's a pun here about "lacking vision"... Oh well, I shouldn't be surprised anyway that I enjoy my own ideas more than anyone else seems to. "Why would you want that?" has pretty much been par for the course my whole life; playing D&D lately has felt no different.  :/

 I'm late to this and necroing the comment, but I think it's hugely useful and a fantastic idea to make it short range like this. I get it about these kinds of ideas not being understood. it's rough being a 'Glass is too big' kind of person. 

I might suggest make it range:touch, but it's a great idea.  I'd probably call it a lv 2 spell.  It is highly flexible but limited. I'd suggest cutting down the ingredients for the components, too, and making it cost 5gp. 

Some people can only think in '1e Classic Dungeoneering' terms and it's sad. The 'Old School' went away for good reason.

What did you end up going with?

Quote from BladeGod >>

yeah no, its been clarified that a changelings shapechange is not see throughable with truesight, as when they shapechange that is their "original" form that is changing, its not some new form, they are changing who they are

Citation please, because changelings are shapechangers (the racial trait is literally called shapechange) and truesight literally says it lets you see the true form of shapechangers, it's pretty explicitly going to affect changelings just like any other shapechangers.

What would be the "true form" of a creature with no true form?  Maybe an androgynous shape?  Something plain and appearing unformed?

Quote from Dhoorguun >>

What would be the "true form" of a creature with no true form?  Maybe an androgynous shape?  Something plain and appearing unformed?

A lot of the official artwork for changelings does show a kind of "neutral" form usually with pale skin and eyes, white hair etc., even if you just interpret that as some kind of "fluid" or transitioning state it seems reasonable a creature with truesight would see it.

It's pure DM and/or player fiat though since we're not really told what seeing a true form means exactly; for example, if an adult gold dragon transforms into a cat, what do you see? A tiny little dragon? What about something with an even less compatible shape like a bird or a humanoid?

Personally I think of it more like seeing through an illusion, since that's something else truesight does, so they see the transformed form as somehow insubstantial, or exuding some aura of falsehood, and if they choose to focus upon and look "through" it they can see what the creature truly is, perhaps as a mental image or such, so it doesn't matter how it fits within the space.

But it's a classic example of being told what something do mechanically, but not enough about what it's supposed to be doing narratively. 😉