What happens when true polymorph is cast on a conjured creature?

Question

The scenario is as follows:

1. Shem the Wizard first casts Conjure Elemental into a Glyph of Warding, setting it up to summon a Fire Elemental.
2. Shem triggers the glyph, summoning the elemental with no need to concentrate on it. The elemental is friendly to them for the duration (one full hour), and is set to vanish again at the end of the hour.
3. Shem casts True Polymorph on said elemental, transforming it into, for simplicity's sake, an Air Elemental.

What happens at the end of the one hour when the original Conjure Elemental expires?

What if Shem in step 3. true polymorphs the elemental into a chamberpot?

A good answer would address both (a) if the creature remains after the original summoning duration expires and (b) if the creature is friendly towards the caster in its transformed state (before and, if it remained, after the duration of the original summoning ending).

PS: I’m aware that allowing the polymorphed creature to permanently stick around would be exploitable and would allow you to build an army of minions, one a day. And as a DM I’d shut that down. But on spell level 9 you already can create unlimited numbers of conjured creatures with the Simulacrum exploit, so I’m not concerned about that. I’m curious what would happen here under RAW.

Answer 1

This is a question about the term "game statistics". True polymorph says:

The target’s game statistics, including mental ability scores, are replaced by the statistics of the new form. It retains its alignment and personality.

So your question is, simply: is "this creature disappears when the conjure elemental spell ends" a game statistic? If so, it is overwritten by true polymorph; if not, it isn't.

We have a whole question about the definition of "game statistics": What all is included in a creature's game statistics? and the above spell effect is not a game statistic.

So the creature still vanishes even if polymorphed.

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You've separately asked what happens with the lines from Conjure Elemental about the creature being friendly or hostile. These lines are also not part of the creature's "game statistics," so they also are not overwritten by true polymorph.

Answer 2

The elemental might remain in its new form, but it would not be friendly

From my perspective, casting conjure elemental targets a creature on one of the elemental planes, puts it under a behavioral compulsion, and then temporarily drags it to this plane. All the while it is here, it is still under the effects of the spell, which is why you normally need to maintain concentration on the spell itself. Thus, for me, this is not a question of what happens to the "statistics" of the creature when it is polymorphed, but rather, what happens to any spells that are on it. Do they remain in effect, are they suppressed, or do they fall off?

From Sage Advice:

Can a creature under the effects of polymorph have other spell effects on them [sic], or are those game statistics also replaced by the those of the beast form? Polymorph replaces only the target’s character sheet or stat block with the stat block of the chosen form. Other effects, such as other spells, still exist.

I would consider all the effects of the conjuration (both the compelled behavior and the summoning duration) to be the 'other effects, such as other spells,' that still exist, even after polymorph.

At the end of the summon elemental duration, a fire elemental that was not polymorphed would be sent back to the Plane of Fire. But suppose nearing the end of its conjured duration you change its form with true polymorph. What happens at the end of the original hour? Would altering its form be enough to suppress or dispel the original conjuration, and its effects? It would make no sense to send an air elemental 'back' to the Plane of Fire, after all. In essence, this is asking the same question as whether a creature under the effects of a Hold Person spell is still held after it has been polymorphed into something that is no longer a Humanoid, that is, no longer a valid target for Hold Person. And there is no RAW that answers this, but there are two possibilities. Either the spell effects apply, the original conjure duration asserts itself, and the true polymorphed creature (in whatever its current form may be) disappears, rendering your question moot, or the polymorph spell has successfully removed or suppressed the status of the elemental as a 'conjured being of limited duration'. If this part of spell is not active when its duration expires, than the new form persists.

Assuming the new form remains, we now need to know its personality, and True Polymorph says it does not change the creature's "alignment and personality." So what can we go by?

Conjure Elemental says:

The elemental is friendly to you and your companions for the duration...It obeys any verbal commands that you issue to it (no action required by you). If you don't issue any commands to the elemental, it defends itself from hostile creatures but otherwise takes no actions.

However, it also says:

If your concentration is broken, the elemental doesn't disappear. Instead, you lose control of the elemental, it becomes hostile toward you and your companions, and it might attack. An uncontrolled elemental can't be dismissed by you, and it disappears 1 hour after you summoned it.

From these two quotes, we can extract what the "personality" of the elemental is apart from the rules regarding its control and persistence: it obeys you only because you are controlling it. You are issuing it commands it is required to follow, not requesting assistance it is freely offering. When it is not given commands, it makes no move to help you. It simply defends itself. It does only what you require it to do, and no more - it would attack you if it could.

You might be able to get around the Concentration requirement for control by using Glyph of Warding. You might be able to get around the duration of the Conjure Elemental spell by using True Polymorph, such that it is no longer in the form of a conjured elemental that will disappear an hour after summoned. Thus, you might get an air elemental that is not summoned and has no duration. But that air elemental retains the fundamental hostility to you that is part of its basic personality. It is not your minion. Unless you have another means of controlling it, it is not under your control, as any control you exerted was based on its status as a creature you had summoned - which it no longer is. At the end of the duration of the original conjure elemental spell, it is now a free-willed air elemental that is hostile to you and may attack. In fact, it might even be such as soon as you have polymorphed it.

Turning it into a chamber pot will get around this animosity, true enough - but in my experience, chamber pots don't make the most effective minions.

Answer 3

The DM will need to adjudicate

The rules do not cover this specific situation, so the DM will need to adjudicate.

The true polymorphed elemental probably doesn't stick around.

In game terms it is reasonable that this won't work. While "true polymorph" changes a the target's "game statistics", it does not change its fundamental essence. It is still itself, deep down. Probably. After all, game statistics are an abstract representation, and do not account for everything. Things such as the soul, family, current location, origin, are not accounted for in game statistics.

Transforming it into an object instead of a creature doesn't change things.

However, there's enough ambiguity in the spell for interpretation and argument, so the DM will need to adjudicate.

Is a true polymorphed elemental friendly?

The conjure elemental spell says:

The elemental is friendly to you and your companions for the duration.

The DM will need to determine if the elemental is friendly beyond an hour.

It's reasonable that even if true polymorph keeps the elemental beyond an hour, it's no longer friendly, since the conjure elemental spell ended. However, there's no reason to believe it becomes hostile, either.

Contrast with planar binding:

If the creature was summoned or created by another spell, that spell's duration is extended to match the duration of this spell.

Planar binding explicitly extends the duration of conjure elemental. True polymorph shouldn't.

A friendly, permanent elemental definitely shouldn't work

This is game-breaking if not checked. At least, it's game-breaking if the elemental is friendly. If the elemental is indifferent, then it's not particularly game-breaking, at least in this instance.

There are many places in the rules where, with the right interpretation, the game is broken, and this is one of them.

The player is probably hoping to find leverage to gain a permanently loyal minion; that's okay, some players and tables like trying to exploit the rules.

If allowed once, the caster gets a permanent minion, and the player gains an extra action or attack. If allowed multiple times, the caster gains many minions, as many as time allows, and the game is broken.

The rules-as-written interpretation

RAW, it's ambiguous. The wording of conjure elemental supports that the elemental is neither friendly nor hostile if the spell runs out and the elemental is still around.

The effects of true polymorph on the elemental are ambiguous at best.

You can find endless places in the rules where the rules don't account for every possible situation. That's actually in the rules, in the introduction to the DMG:

The rules don’t account for every possible situation that might arise during a typical D&D session.

This is one of those situations.

So, the actual RAW answer, is, the rules don't say, it's up to the DM.

Running the game

It's the DM's job to shut down or limit game-breaking actions. The DM is in charge, not the rules. The DM needs to keep the game playable.

Rules-lawyers

A rules lawyer may argue with you. If you enjoy it, great, argue away. If not, game balance and playability are a perfectly valid reason to disallow something.

You do not need a rationale for this. You can just disallow it.

The character can try it

You are also free to rely on "How to play":

1. The DM describes the environment.
2. The players describe what they want to do.
3. The DM narrates the results of the adventurers’ actions.

You can certainly tell the player to try it in-game, and then narrate that it fails. You can have this conversation out-of-session.

Ruling or table rule

It is perfectly reasonable to simply disallow this as a table rule.

It may help if you explain to the player that this can't work, because if it works for the player, it works for everyone else, and the world is full of permanent elementals.

Allowing it once

There may be circumstances where you may with to allow it once. If you want, you can rationalize this in game. You can allow the character to discover knowledge that suggests it can happen under a certain set of unique conditions, for instance.

You can also simply tell the player that it only works once, because that's how magic works. The wish spell does not give a rationale for the lifetime limit, it just imposes it. Similarly, you can allow the player to have this one time only.

My experience with summoned elementals

You don't need this trick to break the game with summoned elementals (or other creatures). If the DM allows planar binding to work on elementals then a character can easily gain a small number of summoned elementals bound for a few days. That's more than enough for the character to have many minions attacking per turn. We experienced this in a game I was in. The consensus amongst the players was, it wasn't fun. We agreed to limit such conjured/summoned minions in number and frequency. It worked much better after that.

If you are the player

You might want to work it out with your DM ahead of time, so that you don't use up session time examining the subject in detail. Furthermore, most DMs appreciate not being surprised at the table with these sorts of shenanigans.

Answer 4

The wording on different summoning spells is inconsistent and can depend on interpretation.

For the example you gave, Conjure Elemental states (emphasis mine):

The elemental disappears when it drops to 0 hit points or when the spell ends.

This can be interpreted as: if the creature is no longer an elemental it does not disappear.

In your example the creature is still an elemental and would thus vanish, it is still the creature that was summoned by the spell and true polymorph does not state this changes. But for completeness sake, let's consider true polymorphing into different creature types.

The above ruling is by strict reading of the spell not wrong, but I would argue it does not feel correct. "The elemental" is merely an extremely poorly constructed demonstrative word, it is used to reference the creature that was summoned and not as a restriction on when it does or doesn't disappear.

This second interpretation also provides a more consistent ruling when looking at other, often newer, summoning spells like Summon Elemental which state:

The creature disappears when it drops to 0 hit points or when the spell ends.

As you can see, they have started using "the creature" instead of going into unnecessary detail about the nature of said creature. Even after a true polymorph it is still the same creature, although perhaps not of the same creature type. With this wording it is clear the true polymorphed creature will disappear like normal.

This does bring up using True Polymorph to transform a creature into an object, which means that regardless of the summoning spell used there is no longer a "creature" to let disappear. So the object stays for as long as it stays on object. Although still perhaps a bit silly, this ruling would be consistent across all summoning spells.

In conclusion, due to the wording of many older summoning spells a technically correct ruling can be made for the creature to stay longer if it is currently of a different creature type than what is written in the spell. Other, often newer, summoning spells are more clearly worded and make it clear their summoned creature(s) should disappear like normal even when true polymorphed into a different creature type. For a consistent, and perhaps intended, ruling I would suggest to let the summoned creatures disappear like normal regardless of which summoning spell was used. If a creature is transformed into an object, there is no difference between summoning spell wordings so letting it stay till dispelled can feel more acceptable.