Is it possible to make crafting materials, like adamantine, out of a goblin or such using the True Polymorph spell for the full duration of the spell? On a side note, while adamantine is mentioned in the Monster Manual, I didn't see it in the PHB. Is that something else that will be fleshed out in the DM guide?

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    \$\begingroup\$ I can't find anything against it, but wouldn't it be pretty bad idea? I mean, can't this spell be reversed, dispelled etc? Of so, you are without a sword and there is angry monster next to you now. \$\endgroup\$
    – Mołot
    Commented Nov 6, 2014 at 23:03
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    \$\begingroup\$ @Mołot Or half an angry goblin xD \$\endgroup\$
    – aebabis
    Commented Nov 6, 2014 at 23:13
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    \$\begingroup\$ @acbabis so... messy... All this blood! But on more serious note, lost time and effort on sword was my main concern. At levels when this spell is available single goblin isn't really a problem anyway. \$\endgroup\$
    – Mołot
    Commented Nov 6, 2014 at 23:17
  • \$\begingroup\$ And really, why adamantine at all when most creatures' resistance is removed with a magic weapon which boosts to-hit and damage. Sure it's possible, but by the time it is, it's basically completely pointless \$\endgroup\$
    – wax eagle
    Commented Nov 7, 2014 at 0:10
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    \$\begingroup\$ Why wouldn't you just transform the goblin into the sword and skip the middle step entirely? \$\endgroup\$ Commented Jul 9, 2015 at 19:58

2 Answers 2


I don't see why not.

It's not exactly a practical way of going about things, but it would be possible (by 17th level money isn't really an object). The spell says you can transform a creature into an object. Turning a Goblin into a lump of adamantine is totally within that realm of possibility (tbh, why stop there, I'd dream a bit bigger, and maybe a bit more valuable, though we don't have a gold price on adamantine in 5e at this time).

When the measuring stick of this is literally comparing it to wish, converting a goblin into a hunk of metal really isn't a big deal.

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    \$\begingroup\$ If you're aiming for efficiency, you could always wish that all goblins were adamantine. \$\endgroup\$
    – wax eagle
    Commented Nov 7, 2014 at 0:15
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    \$\begingroup\$ I would advise against that wish. While I'm DM'ing, I would interpret that wish as: "The goblins remain living, mobile, sentient, but are also made of adamantine." Then have the campaign become: How to stop the world from being taken over by adamantine goblins. \$\endgroup\$
    – John Evans
    Commented Nov 7, 2014 at 0:21
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    \$\begingroup\$ @JohnEvans absitively-posilutely. \$\endgroup\$
    – wax eagle
    Commented Nov 7, 2014 at 0:37
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    \$\begingroup\$ @JohnEvans LOOKS LIKE I'VE GOT MY NEXT PLOT HOOK. \$\endgroup\$ Commented Apr 6, 2017 at 13:34
  • \$\begingroup\$ Just a reminder: A single lucky (or high slot) casting of Dispel Magic will take away your new sword and restore the angry goblin to their original form. And even low level folks will be able to tell something is up, as Detect Magic will show a clear ongoing aura of Transmutation magic. \$\endgroup\$ Commented Oct 26, 2022 at 22:37

The true polymorph spell says:

Choose one creature...that you can see within range. You transform...the creature into a nonmagical object...

By choosing the creature, you have made the creature into the target of the spell. The object into which it transforms is also under the effect of the spell. The original creature is still the target, even though it only exists in a conceptual (not physical) sense. You know that the game treats the creature as if it still exists because it will be restored when you use dispel magic, and because the creature itself can be seen with truesight.

If you turn a creature into an object, it transforms along with whatever it is wearing and carrying into that form, as long as the object’s size is no larger than the creature’s size. The creature’s statistics become those of the object...

Since the creature's statistics are now those of the object, the creature's hp are those of the object as well. This is important because if the object's hp become zero, then the creature's hp become zero, and this ends the spell.

The spell lasts for the duration [Concentration; up to one hour], or until the target drops to 0 hit points or dies. If you concentrate on this spell for the full duration, the spell lasts until it is dispelled.

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

There is some disagreement about whether concentrating on the spell for the entire duration means that the "or until the target drops to 0 hit points or dies" still applies. Fortunately that is largely irrelevant because of the next sentence; the spell has no effect on a creature with 0 hp. If the target of the spell drops to 0hp, the spell ends. This is true even if the spell has been concentrated on for the full duration; it is an overarching condition that can end the spell. Thus while concentration still applies the spell has four end conditions; it will end when the concentration ends, when it is dispelled, when the target drops to 0hp, or when the target dies. After the spell has become 'permanent', it has only two end conditions - being dispelled or if the target is at 0hp. Thus in turning your erstwhile goblin into a sword, you will need to take care to neither dispel the polymorph nor drop the block of adamantine to 0hp1.

Normally the game does not worry about the hp of objects unless something is damaging them. The DMG section on statistics for objects (246, 247) focusses entirely on how to break or destroy them, including saying:

Hit Points. An object's hit points measure how much damage it can take before losing its structural integrity.

Damaging a polymorphed object should at some point reduce its hp to zero, and thus the target creature to 0hp, and thus end the spell effect. Your central problem, then, is how to change your adamantine block into a sword without reducing the block to 0hp. You will need to radically change its shape without it losing its structural integrity.

First off, melting and casting into a mold is probably out. Although there is not a clear consensus or an official ruling, it seems like most DMs would not consider liquids to be objects. Even if the molten adamantine was an object, it is pretty clear that the solid block of adamantine lost its structural integrity in becoming liquid.

Thus, to make your sword you would be forging the metal2. Here, too, the DM would need to determine whether the process of forging was causing the metal block to lose its structural integrity. Personally, I would probably rule that hot forging would release the goblin, warm forging might, but cold forging, which in some ways actually strengthens the metal, would not count as damaging and would be sure to keep the spell intact.

D&D grognards know that cold-forged weapons are more effective against demons and even some undead. Time was when you couldn't travel the Marklands without someone greeting you with "Cold iron avail you!" Even in 3.5 it was claimed that the holy avenger swords used by paladins were made from cold-forged iron. Given that, I have to wonder whether this was because their efficacy came from true polymorphing a celestial into the iron from which the sword was made.

1One might argue that "this spell has no effect on a shapechanger or a creature with 0 hit points" refers to targeting rather than duration, but this claim is not supported by context. First, if the clause was about targeting it should go earlier in the spell description, before the effects of the spell are described ("you transform") and not after the section on duration. Second, it does not say "This spell cannot target a shapechanger or a creature with 0 hit points". It does not say "You cannot choose..." It does not say "This spell will not affect..." (future tense). Rather, it says, present tense, this spell has no effect. Thus anything that reduces the original target creature to 0hp will end the spell effect.

This interpretation is supported by a JC tweet:

@DMJazzyHands once a true polymorph spell is made permanent from concentrating for the full duration, does reducing that creature to 0hp still cause them to revert to their original form?
@JeremyECrawford The text of the spell says it has no effect on a creature with 0 hit points. That statement is made after the bit about lasting until dispelled. At 0 hit points? The transformation ends.

2Then again, you might just be using fabricate. However, a sword is certainly an item that 'requires a high degree of craftsmanship', and it is not every wizard that has tool proficiency in smith's tools.

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    \$\begingroup\$ I am not the downvote, but reading this, it's not clear to me if the resulting object still would count as a creature. Intuitively, as objects are inanimate, non-living things, and a creatures are informally living or animate or have a creature stat block, I'd think it is an object, not a creature, and statements about the creature's hp being 0 would not apply anymore. At the same time, it is not dead, and there is a "latent" creature in there somewhere. So, not sure this is wrong, but I think this is maybe more of a DM call how to deal with it. \$\endgroup\$ Commented Apr 26, 2023 at 5:18
  • \$\begingroup\$ @GroodytheHobgoblin The metal block is definitely an object, not a creature. But the spell tells us that "The creature’s statistics become those of the object..." This ties the two things together - the "latent" creature now has the hp of the object. If the object's hp become 0, so do the creature's - by the description of the spell. \$\endgroup\$
    – Kirt
    Commented Apr 26, 2023 at 5:57

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