The deep scion is a monster detailed in the fifth edition supplement Volo's Guide to Monsters (p. 135). I'm unaware if deep scions have featured in previous editions of DnD.

Deep scions are people who have been subjected to a ritual that transforms them into an evil shapechanger capable of:

wearing the mind and body of the person it once was as a sort of mask.

Imagining that a coastal village has been infiltrated by deep scions, who are stealing away residents and assimilating them one by one, once the wider threat has been discovered (perhaps a group of deep scions surprised while in piscine form) how would other individual deep scions be unmasked?

Deep scions seem to be extremely capable of maintaining their humaniod disguises in the long term, so having dealt with / questioned all of the obvious candidates how would PCs know whether the threat had been neutralised?

Is there any relevant deep scions lore in other supplements, or even other editions, that might provide some transferable guidance?


How you unmask any cultist

As spells go, detect thoughts (a 2nd level spell) will help, just as half of other divination spells might too. I am going to focus on even more basic techniques, though.

Cultists, generally, look like normal people (because they are), just like Deep Scions do (when polymorphed). What makes them different is their behavior. They meet up, scheme, plan, leave dead bodies and strange diagrams in their wake. They visit forbidden places, act out forbidden rituals, keeps secrets.

A smart PC can detect this through careful observation, snooping around and meddling and being intusive. Maybe even provoking their hostility. Once they have enough evidence, they go for the kill – either literally or figuratively.

  • \$\begingroup\$ @Tiggerous But true form probably does refer to the scion form, not the humanoid one, doesn't it? Could be a misprint? \$\endgroup\$ – J.E Sep 7 '18 at 9:31
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    \$\begingroup\$ @Tiggerous it’s true form, in the context of that text block, is the original form of the person they once were (the shapechanger portions of the text allows them to turn into a human-piscine form) \$\endgroup\$ – illustro Sep 7 '18 at 9:32
  • \$\begingroup\$ @illustro then it seems I misread it, time to edit that out then. \$\endgroup\$ – J.E Sep 7 '18 at 9:34

Use zone of truth

Clerics are amazing for this (as are bards, and paladins).

Just use zone of truth; it is a 2nd-level spell with a Charisma save to resist, and you know if they managed to resist it.

After they fail, they must answer all questions truthfully (or they can refuse to answer).

Then ask them if they are a deep scion; if they don't answer, kill them.


I have found no references to deep scions in other 5e supplements or other materials from other editions or other products, or any other sources, for that matter. The word scion generally means "a lineal descendant of a notable family".

To expand on J.E's answer, PCs sleuthing around some town might uncover all manner of strange behavior, and might have ample opportunities to make perception and insight checks regarding questionable behavior by normal townspeople and deep scions, both. Is that strange old guy sitting on the hotel porch staring into the sea just a strange old guy, or is there something fishy about him, really really fishy? Is that friendly young woman yearning to pick up a sword and take up adventuring just an exceptionally strong and friendly young lass, or is there something fishy about him, really really fishy?

And, of course, the scions' underwater master might have something to say about having its watery schemes exposed. "Curse you, you meddling kids!"


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