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A spawn of Kyuss is clearly a single creature but is infested with worms, and the worms are the real threat. If you cast polymorph on the creature, is the polymorphed creature still infested with worms? Are the worms somehow expelled from the creature? Or would the worms be absorbed by the spell as if they were gear? This is somewhat related to What happens when you cast the Polymorph spell on a swarm?, but a little different since there is a clear target.

If the worms are absorbed as gear, would this suggest that the same happens when casting polymorph on someone carrying a smaller creature? If the worms are expelled, does that mean polymorph could be used as an alternative to cure the disease since it expels foreign bodies?

This is for a game I'm running, so I know I can always just make a ruling, but I have a somewhat litigious group (including myself), and I like to have some rationale for rulings when I can.

My current opinion (based on Do diseases carry over from polymorph?) is that the worms count as a disease so would be carried over, along with the "Burrowing worm" ability. Does this seem the more "correct" answer? Or is there something else RAW or RAI that suggests otherwise?

Akixkisu
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aquavitae
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2 Answers2

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The Spawn of Kyuss would polymorph like any regular creature.

Regardless of the answers and different approaches to What happens when you cast the Polymorph spell on a swarm?

A Spawn of Kyuss is one entity - not a swarm, but the ejected new entities created by the Burrowing Worm feature are new entities. Polymorph targets a creature, and thus the Spawn of Kyuss would polymorph like any regular creature.

The target's game statistics, including mental ability scores, are replaced by the statistics of the chosen beast. It retains its alignment and personality.

The chosen beast has no added worm related features as part of its game statistics.

The other undead created by the Burrowing Worm feature are unaffected - each latched worm is one independent creature (a tiny undead). You will notice that the book refers to swarms as a swarm (see in particular MM 337-338), and the Spawn of Kyuss lacks any description like that.

The description of the spawn refers to The Plague of Worms, but it is also explicit:

[...] Once inside the brain, the worm kills its host and animates the corpse, transforming it into a spawn of Kyuss that breeds more worms. [...]

We have a former creature that the worms kill, and then they create a spawn. Nothing indicates that Polymorph would remove any aspect of that entity when it ends.

Akixkisu
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2

RAW, the worms are not carried on the new form.

The text of the Polymorph spell says (emphasis mine):

[...] The target's game statistics, including mental ability scores, are replaced by the statistics of the chosen beast. [...] The creature is limited in the actions it can perform by the nature of its new form, and it can't speak, cast spells, or take any other action that requires hands or speech.

Since the entire stat block is substituted by the one of the new form and the worms and the Burrowing Worm Action of the Spawn of Kyuss is part of the stat block of the latter, such worms are no more present in the new form.

A loose interpretation suggests that the worms are present also in the new form.

The spawn of Kyuss possesses the Worms trait (emphasis in bold mine):

Worms. If the spawn of Kyuss is targeted by an effect that cures disease or removes a curse, all the worms infesting it wither away, and it loses its Burrowing Worm action.

This trait suggest that such worms can be considered both as a disease and as a curse\$^1\$, and the can be removed both via Remove Curse or Heal spells, for example: in this case the DM has to make a ruling. They are hence carried on the new form, if one accepts this answer. But the new stat block does not include the Burrowing Worms Action (per Polymorph description), even if the worms are present: in this case the DM should decide if the new form is able to thrown the worms to a creature/enemy.

\$^1\$ A curse that causes a disease, maybe: it is all up to the DM.

Eddymage
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