I am currently DMing a campaign where there is a wizard with the Identify spell, the bane of my existence.

Identify allows him to learn the properties of literally every single item the party encounters. I understand that Identify uses resources (either spell slots or time), which is relevant in a dungeon with wandering monsters, but out of perilous situations there are not many drawbacks.

I am going to give the characters a really cool artifact sometime in the future, with a lot of mysterious characteristics that I want them to find out slowly. One action, and all the properties are discovered.

I am creating a shop called Ocean's Potions In which a water genasi wizard creates a whole bunch of random potions in pairs, so the PC's can drink one to find out the characteristics are, and then use the other sister potion when it is relevant in the future. There will be a lot of cool, beneficial, and random potion effects that will effect them when they try them. However, Identify can let them choose the best in one action, and let benefit from the effects twice.

I understand that spells should do what they say they do, but how can I get around this spell ruining everything?

Put a Nondetection effect on the item

The spell Nondetection has the explicit effect that its target becomes unable to be targeted by Divination magic. Identify is a Divination spell. Ergo, an object that has Nondetection cast on it will not be targettable by the Identify spell.

Nondetection

For the duration, you hide a target that you touch from divination magic. The target can be a willing creature or a place or an object no larger than 10 feet in any dimension. The target can't be targeted by any divination magic or perceived through magical scrying sensors.

—Player's Handbook, pg. 263

You will potentially run into the issue that RAW, Nondetection only lasts 8 hours. As DM, however, it's not outside your purview to simply give the object a permanent (maybe dispellable with Dispel Magic or Remove Curse?) version of Nondetection. That way, your players won't be able to short-cut to learning the features of the item with a single spell. And if you do make the Nondetection effect dispellable, then it leaves the door open for your players to feel clever if they do figure out how to remove the Nondetection effect, though it does risk players simply causing the problem you were trying to prevent.

Use the "More Difficult Identification" rules in the Dungeon Master's Guide

In the Dungeon Master's Guide, there are optional rules that you can use to make identifying objects more difficult.

More Difficult Identification

If you prefer magic items to have a greater mystique, consider removing the ability to identify the properties of a magic item during a short rest, and require the identify spell, experimentation, or both to reveal what a magic item does.

—Dungeon Master's Guide, pg. 136

^{Emphasis mine}

If you want to make identification more difficult, you could require that an item require both experimentation and the Identify spell to determine its full properties. Maybe the spell reveals some surface level details and proper experimentation reveals the hidden depths.

Tell them identify doesn't work on these items, for reasons that hint at game lore

Despite the matter-of-fact wording in the identify spell, there is certainly precedent for items whose properties cannot be revealed by identify, or even items for which identify reveals false information. For example, in the DMG section on cursed items (emphasis mine):

A magic item’s description specifies whether the item is cursed. Most methods of identifying items, including the identify spell, fail to reveal such a curse, although lore might hint at it. A curse should be a surprise to the item’s user when the curse’s effects are revealed.

Obviously, your potions are not cursed items, but a similar logic applies: the whole point is that the potion's effects are meant to be a surprise. You can even do this in a way that makes the caster of identify feel like they got something useful out of their spell, even though they don't discover the actual function of the potion. Rather than simply saying "the spell fails", you can tell them that the identify spell reveals the potion's function, which is to produce a random effect when consumed. Make up some explanation, such as saying that the potions were created with fundamentally chaotic energies, so it's impossible to predict the effect without using the potion, because the effect isn't even determined until the potion is drunk. You can tell them that the matched pairs are quantum-entangled or some magic-sounding equivalent, which explains why the pairs both produce the same effect even though they're both "random". The point is, when the identify spell fails, you can have it "fail" in a way that rewards your players with hints at new and interesting lore about your game world.

Regarding the "really cool artifact with a lot of mysterious characteristics", I would say that it's entirely fair to just tell your players that the identify spell doesn't work. It's not at all unusual for identify to fail on such powerful and unique artifacts. Again, you can make up some reason for this that expands upon the lore of the game world. For example:

• Was the artifact created by a powerful, paranoid wizard? Then that wizard would certainly have shielded their creation from divination magic, lest it be discovered by other wizards. In fact, the identify spell tells the caster that this item is non-magical, which is clearly at odds with the magical properties they've already observed, hinting at the fact that this artifact is something special.


• Was the artifact created by long-forgotten magics from another plane? Perhaps it is simply outside the parameters of the standard identify spell, which was only designed to identify types of magic that was known at the time. When cast, the identify spell "works", but the description it returns is unintelligible gibberish. Perhaps your players will later find an old spellbook from a bygone era containing an archaic variant of identify does not have this limitation.


• Was the artifact created by a deity? Perhaps the deity didn't want it to be identified, and so they simply used their godly powers to make it so. Think about how that god's powers would manifest to prevent the identification. Perhaps the caster remembers receiving a full description of the item's properties, but for some unknown reason they are unable to recall a single word of that description.

Remember that you don't have to tell them exactly why the spell doesn't work (e.g. "a wizard shielded it from divination magic"); instead, just tell them what weird thing happens (e.g. "the item reads as non-magical even though you know this is demonstrably false"). This way, instead of identify ruining the mystery, the spell makes things even more mysterious, which hopefully makes your players even more invested in solving the mystery.

Change the rules

Between identify, and the rules for characters figuring out what items do by spending a short rest with them (DMG p. 136), 5e is signalling to us that by design, figuring out what magic items do should not be a challenge. I can see the argument: from a player's standpoint, they might just want to use their treasure and not jump through hoops to do so; they feel like they've already earned it by finding / acquiring it. But as someone who is primarily a DM, I see the other argument too.

Bottom line: decide whether or not you agree with that aspect of 5e. If you do, just let it go, if you don't, change the rules. As-is, it is almost trivial to identify a magic item. You, as the DM, are well within your right to change rules. Doing it mid-game with a precedent already set is another matter. If you wanted to go this route, you could say that those techniques only work on, e.g. uncommon magic items (thereby saving yourself from this issue when the party starts discovering more powerful items). You'll have to make a judgement call regarding what change, if any, is appropriate given the established precedent.

Talk to your players about this

For any situation where you want to change the rules (either mid-campaign or pre-campaign) you should talk to your players about the rule change and why you want to make it. Ultimately any change to the rules should be making the game more fun for you and your players.

If your players like the proposed rule changes then great, you've gotten everyone on the same page.

You should be prepared, however, for your players to say that your suggested rules changes are not something they will enjoy. If that's the case then listen to them. It may mean you need to change some detail of your plot, or how you award the magic items.

Let's say your players want to keep the status quo with identity: Using your potion shop as an example, you could change Ocean's Potions to be instead:

• each potion comes with a companion potion, which is required for the magic potion to work on someone


• the price of buying a potion is that the character's drink a "wild magic" potion (which rolls on the sorcerer's Wild Magic table for its effects)


• it just sells one copy of a potion

How can you make identification more difficult?

My house rule for this sort of situation (which I established with my players in a Session 0) is the following:

There are three tiers of items:

• Artifacts


• Magic Items


• Regular Items

Identify (and other related methods of identification) then has the following properties:

• For all items identify will reveal whether or not it's magical


• For non magical items identify will find out what the item is, its classification (martial/non-martial weapon/other item) and its purpose


• For non-cursed magic items
  
  
  
  
  • a ritual identify will get the current beneficial properties
  
  
  • a level 1 identify (using the spell slot not the ritual) will get all of the (current and future) properties of the item
  
  
  • attunement and experimentation will get you some of the properties
  
  
  
  


• For cursed magic items a level 2 identify will reveal the curse's effects


• For Artifacts
  
  
  
  
  • A level 3 identify is required to get the main beneficial properties
  
  
  • A level 4 identify is required to get all the properties
  
  
  • A level 5 identify is required to find out the method of destruction (of which there is only one)
  
  
  
  

In game this tiering is justified as the magic imbued into the item/artifact resisting the magic from the identify spell and the spellcaster has to overcome that magical potential in order to extract the information from it using identify.

This has worked well in the last campaign I ran. The players were happy with the changes, and how they affected their character's decisions (for example, choosing to attune to an item they could not identify despite the risk that it might be cursed was worth the trade off for one player).

What if I don't want to houserule this?

The DMG has a variant rule for making identification of magic items more difficult in your campaign:

Variant: More Difficult Identification

If you prefer magic items to have a greater mystique, consider removing the ability to identify the properties of a magic item during a short rest, and require the identify spell, experimentation, or both to reveal what a magic item does.