Ironically useless enchanments

[Lortime]

Hello friends i love item such as Ring of detect fire Range : touch or a helmet of detect invisible but it blocks your vison or amulet of air breathing.
please list other useless item and enchantments to serve as troll item or bad enchantments.

[The Glyphstone]

Amulet of Air Breathing sounds like a great item to use during an underwater adventure. Now, if it's cursed to shut off when it gets wet, that's more appropriate.

[Maglubiyet]

Schrödinger's Box - summons a cat (maybe dead, maybe alive) only when the box is closed, but the cat vanishes when the box is opened.

A feather fall ring that only works underwater.

Shield of Etherealness - medium shield that turns ethereal when struck

[Segev]

A suit of full plate which casts mage armor on its wearer, as long as it's worn. No, it isn't granting a +X enhancement bonus to armor class. It casts mage armor, granting 4 armor bonus to AC that doesn't stack with the plate. (Technically still useful vs. incorporeal touch attacks.)

[Newtonsolo313]

Shoes of grease: cast grease of floor when worn
Orcish healing club:does 1d8 damage heals for 1d4
Reckless studded leather armor: -3 ac

[Lemmy]

Good ol' Cloak of Invisibility that only turns itself invisible...

[NichG]

Wand of Remove Paralysis (Self)
Type 0 Bag of Holding: Weight multiplier x1, capacity = actual capacity of a mundane bag of the same shape and size.

Even better if you can turn it around and find ways to make them useful again.

Ring of Detect Fire (Touch) + Spectral Hand
Opaque Helmet of Detect Invisible + Scrying ("As with all divination (scrying) spells, the sensor has your full visual acuity, including any magical effects.")

[Koo Rehtorb]

Movable rod.

[Tiri]

Good ol' Cloak of Invisibility that only turns itself invisible...

There's also the Cloak of Invisibility that turns you invisible, but doesn't do the same for itself.

I suppose it's not entirely useless, though. You can still scare children with it.

[Frozen_Feet]

It still hides your face etc. identifying features, so it's much more useful than the other invisible cloak.

But on that note:

Cloak of hiding: hides everyone else from you.

[hymer]

A magical gem that glows softly when in the presence of magic.

[Tiri]

It still hides your face etc. identifying features, so it's much more useful than the other invisible cloak.

The other cloak isn't completely useless either. Invisible material, even if it's only fabric, has lots of applications.

[GloatingSwine]

Amulet of Air Breathing sounds like a great item to use during an underwater adventure. Now, if it's cursed to shut off when it gets wet, that's more appropriate.

An Amulet of Air Breathing would be useful for some kind of aquatic civilisation to interact with land dwellers.

[iceman10058]

Ring of Flying: when activated the ring flies off the finger never to be seen again.

[Inevitability]

I can't believe no one has mentioned the +1 Ring of Extra Ring Slots yet.

[Jormengand]

I can't believe no one has mentioned the +1 Ring of Extra Ring Slots yet.

If it helps, I was about to.

There's also the brilliant "Orb of detect slope" which, when placed freely upon a slope, roughly indicates the gradient and direction of that slope.

Or how about the "Ring of detect rings"? It turns red when there's a ring nearby.

[Newtonsolo313]

Boots of speed:enchantment only applies to the boots
Sword of mending: casts mending on itself as a bonus action does not function when chipped or broken
Wand of detect self: detects whether the user is within 100ft of wand
Plate armor of burning: casts heat metal on armor no concentration

[GloatingSwine]

Plate armor of burning: casts heat metal on armor no concentration

Get yourself some kind of fire resistance/immunity and play the sweatiest grappler ever...

[JoshuaZ]

A magical gem that glows softly when in the presence of magic.

Autodetects anti-magic fields and similar areas.

[Newtonsolo313]

Get yourself some kind of fire resistance/immunity and play the sweatiest grappler ever...

Ninjas can't catch me if I'm on fire

[Inevitability]

Get yourself some kind of fire resistance/immunity and play the sweatiest grappler ever...

Even better: put it on an iron golem.

[JNAProductions]

Um...

Uh...

Bow-seeking arrow?

[Tiri]

Um...

Uh...

Bow-seeking arrow?

That could be handy in an archery battle. Attach explosives or something similarly destructive for even greater effect.

[JNAProductions]

Except it would target the nearest bow. Yours.

[TheCountAlucard]

Except it would target the nearest bow. Yours.

Unless you're not carrying a bow. Arrows aren't exactly the easiest thing to throw, but it can be done.

[Inevitability]

Unless you're not carrying a bow. Arrows aren't exactly the easiest thing to throw, but it can be done.

Also, Launch Item is a thing.

[Celestia]

Cloak that turns you invisible only when no one is looking at you.
Helmet that grants darkvision but only when exposed to light.
Boots that grant tremorsense but only when you're flying.
Stone that glows when Detect Magic is cast upon it.
Ring of Sustenance that only works for constructs.
Ring that grants immunity to fire but only works for creatures with the fire subtype.
Amulet that projects an anti-magic field that can only be worn by wizards.
Belt of gender changing that only works for oozes.
A book that lets you play a fantasy game but only if you have friends.

[Tiri]

Amulet that projects an anti-magic field that can only be worn by wizards.

This is easy to use. Just take a level of Wizard, and squeeze all the nonmagical benefits you can out of it.

[hymer]

Autodetects anti-magic fields and similar areas.

Can also be used as paperweight or doorstop.

[JBPuffin]

Hang on, those boots would settle whether King Slime is in fact a king or queen...I need to borrow those.

As for my own offering, a flametongue that only ignites when immersed in water. Maybe you can boil your pasta water with it?