Although this may seem like a very trivial question, I still do not know how to interpret this. Several (sonic) spells and effects, like shatter or shout mention different effects on crystalline creatures.

And yet, there is solely one creature in the MM, the salt mephit (plus possibly animated glass objects), which mentions having such trait, and even then, it is just in the fluff text.

Now I am having trouble believing that this text about crystalline creatures has been added to sonic attacks just for the sake of the salt mephit, which an average group of adventurers might encounter once per career. I also feel that sonic attacks having extra effect on transparent (the other meaning of crystalline, according to ldoce) or invisible creatures, regardless of composition, doesn't make sense.

So how are crystalline creatures defined? Is there more of them in the core MM? Is there more of them elsewhere? When should the players be able to use it?


This is not defined within the game's rules. There is no "crystalline" subtype or similar trait.

For better or worse, fluff-crunch separation wasn't always strictly adhered to in 3.5, particularly in the early books such as the player's handbook.

Examples of creatures that in my opinion should count as crystalline include the Crysmal and Psicrystals. What else (if anything) could apply effectively ends up as a matter for you and your DM to decide.

Some interpretations I have seen:

  • Anything that "looks like crystal". This is what I usually see.
  • Anything fitting a modern chemical definition of Crystal.
  • Anything with the (Earth) subtype. Out of the blue, but this is what I remember some re-implementations of 3.5 (such as the Temple of Elemental Evil video game) using.

I don't remember seeing an official definition, but, of course, that doesn't mean there isn't one. :)

However... MM3 has a certain "Troll, Crystalline". Also, some monsters related to the psionics theme are crystal/crystalline, afaik.

You could also rule that anything made of glass/gems/etc (practically anything that has a crystal-like structure) counts. Think certain golems, gem dragons, crystal beetles and so on.

  • \$\begingroup\$ Thank you for a fast answer. Does this mean that spells like shatter are usually useless (directly against creatures in combat) if my group uses primarily MM1 and other core books, though? \$\endgroup\$
    – kravaros
    Aug 28 '13 at 9:39
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    \$\begingroup\$ You're welcome. :) First of all, I'd definitely wait for other answers (I suppose you'll get some), see what they say. As for the usefulness of shatter and the like: against creatures of the core, you seem to be right. However, you could always spice up your setting with crystalline objects and environments where such spells could provide serious tactical advantage: think cathedrals and courtrooms with huge windows, crystal caves, pre-deployed explosives in glass containers, chandeliers, bespectacled (love this word) opponents who go half-blind without their glasses on and so on... ;) \$\endgroup\$
    – OpaCitiZen
    Aug 28 '13 at 10:35
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    \$\begingroup\$ Many players won't care, but most glass isn't crystaline, and won't be damaged by sound any more than, say, granite would be. However, given that glass objects tend to be thin and fragile (which is to say, they have few hitpoints and little hardness), this typically won't make much difference to how they're affected by sonic damage. In any case, whether glass has realistic or crystal-like properties when exposed to sonic effects is up to each individual table to decide. I mention this because it helps avoid problems brought on by different expectations. \$\endgroup\$
    – GMJoe
    Aug 29 '13 at 4:44
  • \$\begingroup\$ @GMJoe Thanks! You're right - and I'll have to brush up on my physics, I'm afraid. :) \$\endgroup\$
    – OpaCitiZen
    Aug 29 '13 at 5:58

Nearly every single metal on the periodic table has a hexagonal crystalline structure. A sonic wave is like any p-wave. The compression of air molecules in wave form. That's how sound works. Science has proven that pressure waves from bombs, earthquakes, and sonic booms can deform and even break metal objects.

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    \$\begingroup\$ Could you edit this post and write a conclusion that states what this observation means in terms of answering the question? \$\endgroup\$ Jan 1 '16 at 0:11
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    \$\begingroup\$ Hi Clint. Your answer may be factual, but it doesn't actually answer the question in terms of the game it was asked about. Could you please edit your answer to address the specifics of the question and the game? \$\endgroup\$
    – C. Ross
    Jan 1 '16 at 1:26

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