I'm working on a homebrew class that, as one of its features, changes type between Humanoid and another (Aberration, Monstrosity, Fiend depending on subclass). Are there any strange interactions of rules that I should be aware of? The one that comes to mind is becoming immune to Hold/Dominate Person which, frankly, is my intention behind this change rather than a double type

Particularly, I'm interested in less obvious effects that would make it difficult for a PC to be a member of an adventuring party if they aren't or occasionally stop being humanoid - interactions such as suddenly messing with or being unable to benefit from allies' class features, for example.

  • \$\begingroup\$ @NautArch: No, immunity/vulnerability to certain effects is a (so far desirable from a design standpoint) side effect of changing type, which is mostly there because it makes sense for the class. I'm trying to find out if I won't stumble into some kind of really weird rules interaction by allowing it - some existing rule that works off the assumption that all PCs are humanoid, for example. \$\endgroup\$ – vonBoomslang Aug 9 '18 at 13:40
  • \$\begingroup\$ I know there are ones, yes - it's obvious they won't work if you aren't humanoid, or stop working if you suddenly stop being one. Does give me an idea for how to edit though. \$\endgroup\$ – vonBoomslang Aug 9 '18 at 13:48
  • \$\begingroup\$ The clarification for concerns about non-humanoids as character races and interactions with class features seems clear now. Voting to reopen. \$\endgroup\$ – NautArch Aug 9 '18 at 17:09
  • \$\begingroup\$ Voting to keep closed, as it is too broad. We cannot possibly list all features that might key off of this. Maybe for a specific class, or a few. \$\endgroup\$ – Szega Aug 9 '18 at 18:16
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    \$\begingroup\$ @Carcer Then it is still unclear, because we do not know where "too much" starts. \$\endgroup\$ – Szega Aug 9 '18 at 19:44

Wizards currently allows a hybrid humanoid-monstrosity Race

Unearthed Arcana recently released the Centaur and Minotaur Races for playtest. These races are both listed as:

Hybrid Nature You have two creature types: humanoid and monstrosity. You can be affected by a game effect if it works on either of your creature types.

This suggests that there is an existing playtest precedent for multiple creature types/different creature type than Humanoid. However, as it is playtest only, it is unclear as to whether or not Wizards themselves know if it's balanced or if it introduces complications.

Anything that requires a creature type would be affected

Whether or not you decide something is a 'complication' is likely to be opinion-based, but any spell, effect, or ability that requires a certain creature type will be affected by changing creature types.

Examples of spell effects/abilities that will be impacted by changing type

You have already listed Hold Person and Dominate Person, but there are many other spells and effects that include a creature type requirement in their descriptions. This includes things such as

  • Spell Calm Emotions
  • Paladin's Divine Smite
  • Paladin's Divine Sense
  • Warlock's Gaze of Two Minds

There are many more, but whether or not it will cause a complication in your world depends on your specific world, the creatures within it, and the abilities they use and have.

  • \$\begingroup\$ I was asking more for rules-based complications, like some weird interaction or something. \$\endgroup\$ – vonBoomslang Aug 9 '18 at 13:34
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    \$\begingroup\$ @NautArch Perhaps he means class features or something in players' general rules (excluding spell effects) that might interfere with the fact that player is no longer of Humanoid type. \$\endgroup\$ – AntiDrondert Aug 9 '18 at 13:38
  • \$\begingroup\$ @AntiDrondert That's a good way to put it, yes - I'd like to be aware if there's something like "he'll have constant disadvantage to everything for being next to a paladin of X oath" or similar. \$\endgroup\$ – vonBoomslang Aug 9 '18 at 13:43
  • \$\begingroup\$ The Druid gives an inherent precedent to non-humanoid creature types without relying on playtest materials. As Unearthed Arcana is still not perfected, using those examples when there are more established case studies may not be the most helpful if just talking about being a non-Humanoid. However, UA does benefit this question in a specific regard: The samples you're referencing are part-monstrosity which is somewhat related to the question as asked, but is also not entirely-relevant due to their hybrid nature which is counter to vonBoom's stated desire and goal. Just my thoughts to work with. \$\endgroup\$ – Sora Tamashii Aug 9 '18 at 22:12

There probably aren't any significant problems with this ability, but you could avoid any that might exist by slightly changing the way the feature works.

A quick search suggests that though there are plenty of spells that would work differently based on your creature types, there are few, if any, significant effects on standard abilities which would make adventuring life for a character of this kind very difficult.

Challenging the frame, though, rather than worry about the possible rules interactions, you could consider instead having your feature worded something like this:

Dual Nature. When you assume a different creature type, your original type is partially suspended. If an effect would apply to your original type but not your assumed type, you may choose to be treated as your original type for the purposes of that effect. (You are treated as the assumed type for any effect which does normally apply to creatures of that type, even if it would have had a different effect on creatures of your original type).

This way, you always get whatever the benefits would be for becoming your assumed type, you always get the drawbacks that would happen because you're now vulnerable to effects which specifically target that type, but you don't accidentally block yourself from receiving beneficial effects, such as they might be. Without knowing more about the class and the other features it offers, it's difficult to judge if this is in keeping with the theme or if it's potentially a bit overpowering.


Yes and No

As Dan B pointed out, doing this results in issues that not even the game's designers can agree on a conclusive answer for. That said, we do have a Class that can transform itself into other creatures at will, the Druid with its Wild Shape Class Feature. As for interacting with other characters' features and spells, for the most part, the issue is a non-issue. Consider it an occupational hazard of going down this path. Basically, I recommend modeling your Homebrew Class off of the Druid, in terms of restrictions and limitations. While it won't work as an exact 1-to-1, you can use it as a model to generally keep your custom class from causing any major issues. Of course, without more information, I can't exactly give tailored advice, but this isn't the place for that anyways. All I can say is that it will be fine in theory and the issues that come up from it shouldn't be too terribly frequent to be concerned over. If issues do come up, you can adjust the Class to fit the solutions to these complications.


Just be flexible and let your players who select it know that doing so is their choice and they need to accept responsibility for any compatability issues between their character and the rest of the party. This can be great for role-playing and for making things even more dynamic, as long as you pay careful attention to how it plays off of other things in an actual game.

  • \$\begingroup\$ That's actually a really good point - the druid (certainly the Circle of the Moon archetype) is a class which is already built around transforming into a non-humanoid creature on a regular basis (as you don't retain your type when you wildshape). Wild Shape doesn't have any special provisions to deal with unfortunate consequences of not being humanoid so it seems very unlikely that there are actually any real significant issues with the change - or at least that any problems that do exist would affect the druid too, so the class wouldn't be unique in suffering such consequences. \$\endgroup\$ – Carcer Aug 9 '18 at 21:55

There are no new problems

There are already spells and class features that let you change creature type, and even let you stop being a creature. There are complications these abilities introduce to the rules and which the system is poorly equipped to handle (e.g. What happens when you stop being a valid target for a spell? What happens when the developers thought they made it so PCs can't have a thing by saying it only works on beasts or monstrosities or whatnot and then the PCs turn into that?), but there aren't any more complications with the premise of your homebrew than with Wild Shape or polymorph or becoming a Vampire.


Here is a question you need to answer: what happens if you stop being a valid target for a spell?

The answer is not obvious from the PHB. We have a whole question about this topic and the answers are inconclusive: the accepted answer says "the spell ends" with a citation to Sage Advice, and a later answer says "the spell does not end" with a more specific citation to Sage Advice. It seems like nobody, even the designers, has a consensus about what the answer should be.

Here's my recommendation: don't try to generate rules effects by changing creature type, because it's confusing and will lead to arguments. If you want a homebrew class that is part monster and thus immune to dominate person, you should leave the creature type as "humanoid" and then say:

Monstrous mind: because of your heritage, you are immune to mind-affecting spells which require a humanoid target.

That way it's clear to everyone what's going to happen.

  • \$\begingroup\$ This is a homebrew class not race, though. Otherwise, valid points. \$\endgroup\$ – Sora Tamashii Aug 9 '18 at 21:05
  • \$\begingroup\$ "Homebrew class that is part-monster"... wot? Essentially, what OP is describing is more like Wild Shape of Druids, but for a custom class and using non-Humanoid non-Beasts. It's not making the character become inherently part-demon (for example) but, rather, have the ability to transform into a demon, just as Druids transform into Beasts. The circumvention should take that into account. As for your skill "Monstrous Mind" idea, what "heritage"? This isn't stated to be like sorcerer in that regard. Just some things to take under consideration. \$\endgroup\$ – Sora Tamashii Aug 9 '18 at 21:49

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