True Polymorph has the option to transform a creature into an object that cannot be larger than the creature. What about the object's value? Wish has a limit of 25,000 gp for on-label use. Could True Polymorph be used to turn a 2 gp sheep into a massive diamond, or a sheep-sized block of platinum?


2 Answers 2


You can turn it into anything (under the size limit), but you probably won't be able to sell it, and using it is risky

The new highly valuable object is under a permanent effect, not an instantaneous effect. The latter is the only truly permanent change; it's not maintained by magic, so it can't be detected or ended by things that detect or dispel magic.

Since True Polymorph is permanent, it's constantly under the effect of the spell. If you're trying to sell your diamond the size of a sheep, the people you'd be selling it to would almost by definition have the resources for a simple Detect Magic check (if nothing else they can pay someone else to do it for far less than the cost of the diamond), which would reveal an aura of Transmutation magic around it; they'd know it's a fake, and almost certainly refuse to buy it.

Even if you use it yourself to achieve some valuable end (making yourself a suit of adamantine plate mail or whatever), you're just one lucky (or high-level) casting of Dispel Magic away from being suddenly naked with your angry foe restored beside you (or possibly in squishy pieces all over you, depending on how your DM interprets the process of forging a polymorphed foe).

So it works, it's just not going to do you as much good as you might hope.

Probably the best use for it (if your DM doesn't veto) would be making expensive material components during downtime. No need to sell, and depending on the spell, you may be casting it out of combat with no risk of it being dispelled.

  • \$\begingroup\$ Your "angry foe" is a 2gp sheep? \$\endgroup\$
    – Kirt
    Apr 1 at 17:40
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    \$\begingroup\$ @Kirt I wouldn't underestimate a DM that decides to fight shenanigans with more shenanigans. Woolly retribution awaits the greedy. \$\endgroup\$
    – Matthieu
    Apr 2 at 14:27

Theoretically, no - but practically, yes

Where does value come from?

Things that are valuable typically derive their value from being rare, being well-crafted, or being useful. The most valuable items are all three, and in 5e these are magic items. The true polymorph spell, however, cannot be used to create a magic item. Although very powerful, it has other constraints on what it can create - a single object which cannot be extensively altered or crafted. These limitations will come in to play long before the size of the object itself need be considered.

Skill, not size

Some materials are valuable because they are rare. The monetary value of gold, for example, is largely based on its scarcity and the game tries to model that. But most of the value of gold items like jewelry comes not from the material itself, but from the craftwork that is put into them - hours of skilled labor. Consider, for example, some of the largest gold nuggets found on Earth - with values of a few million dollars, and sizes easily within the range of what you could achieve by true-polymorphing a sheep. Or, much smaller, the most expensive gemstones with values around fifty million dollars (but much of that value deriving from their expert cutting and setting).

Now compare those values to other items owned by the ultra-wealthy; things like mega-yachts, whose value comes not so much from the raw materials but the crafting and the ability to monopolize the labor of so many skilled crafters. The cheapest yachts are in the price range of the largest single blocks of gold, and the most expensive ones are still ten to a thousand times more than the most expensive gemstones. You can assuredly get a lot of value from polymorphing something into an expensive material, especially if your DM permits you to create something like a cut gemstone rather than a raw crystal, but there are limits.

But how do you craft it?

To attempt to get around the limit on producing a single object with the spell, what if you make something that can be partitioned? OP, for example, would like to make a massive diamond. How about a sheep-sized diamond block that can then be cut into thousands of individual diamonds?

The problem with this is the nature of the true polymorph spell. As Shadow Ranger notes in their answer, 'lasts until dispelled' is not the same thing as permanent. The spell actually has three end conditions; concentration (solved by waiting an hour), being dispelled (always a problem), and the original creature being reduced to 0hp. For, as the spell says,

This spell has no effect on...a creature with 0 hit points

and since

The creature’s statistics become those of the object

anything you do that would reduce the hp of the object to 0 will then transfer to the 'latent' creature (and this point is developed with more support here). Destroying the structural integrity of the object by partitioning it, melting it down, etc. will thus end the spell. You remain with the constraint of being able to make a single object of value, with limited ability to craft the object.

Who would you sell it to?

As Shadow Ranger also says, anyone with the means to buy expensive objects has the means to verify their authenticity. In a world with transmutation magic, the wealthy will certainly examine potential purchases with detect magic. Note that this spell can be cast as a ritual, and is on the spell lists of no fewer than eight classes, as a first level spell. For more expensive items, dispel magic or even truesight might be employed before purchase - either by individual purchasers or by an established auction house that is certifying the legitimacy of its stock. Also note that in the DMG's list of valuable treasure (134, 135), gems top out at 5000gp and art objects at 7500gp. A wealthy purchaser will surely seek to verify potential purchases long before they approach this maximum value, which sets a much lower limit on what you might be able to sell off undetected.


With such a low limit to what you can get by selling your polymorphed item, probably your best bet is to use the object for yourself. Spell components, especially gemstones, are often 'consumed on casting' and this gets around the non-permanent nature of your object. Even better, such gems can have values greater than anything you would realistically be able to sell them for. Even here there are constraints, though. Some spells you might cast frequently require multi-object components, such as the "gem-encrusted bowl" of heroes feast, that you can't manage with a single cast of polymorph. Others require you to turn the gem to powder before you can use it in the spell. Of course you want to permanently protect your lair with a year's worth of forbiddance castings, but turning to dust that ruby you made through polymorph will end the polymorph before you can cast the forbiddance spell. And sure, you want a sapphire for every valuable thing you own so you can have to have an instant summons on it. You can cast the spell itself using your polymorphed sapphire. But then when you want to bring the item to you, you have to crush the sapphire, which you DM might rule ends the polymorph before the summons takes effect.

Looking through a list of spell components, I think your most expensive polymorph target is turning your sheep into a single 25000gp diamond, which can then be used as the material component of the true resurrection spell and which doesn't need to be crushed before or during casting. If you don't have much use for that particular spell, at least it can set a baseline for your expectations of how much you can personally profit from each true polymorph.

  • \$\begingroup\$ I mean, to be fair, in response to 'anyone who can afford a diamond that size can afford a detect magic,' anyone who pops a True Polymorph to go for that deception can probably also dominate a bard to be extra convincing with the sale and a nystul's magic aura set to false aura the gem as non-magical on detection. There's tons of ways to get away with it in the short term, but it's most likely going to wreck the character's reputation unless proper skullduggery and subterfuge is put into it. \$\endgroup\$ Apr 1 at 21:12
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    \$\begingroup\$ @TheFallen0ne Agreed, it largely then becomes an exercise in 'how much effort do you want to go through to make this sale'? Especially when there are other ways available in this tier to create actual diamonds and destroy your game economy legitimately. \$\endgroup\$
    – Kirt
    Apr 1 at 21:23

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