The Human Guise feat renders one human for all intents and purposes, but does counting as possessing the human subtype necessarily entail counting as possessing human's supertype (humanoid)? For example, would a Metamorphic Master Mimic (possessing the change shape ability through the Transmutation Wizard Specialization School or Oni Sorcerer Bloodline) be subject to lycanthropy if bitten by a werewolf while in human form and possessing this feat?
Human Guise doesn't make you humanoid
Benefit(s): You count as both human and your race for the purpose of taking character options, such as archetypes, feats, spells, traits, and prestige classes. In addition, you count as human for all other effects whenever you would otherwise appear human. For instance, a +1 human bane arrow would deal additional damage to a kitsune with this feat while she was in her human form (as per change shape), but not in her true form. Likewise, such an arrow would deal additional damage to a skinwalker with this feat while she was in her true form, but would not in her bestial form (as per change shape).
This feat was specifically written for Kitsune, which have a type Humanoid (Kitsune), while Humans have a type Humanoid (Human), Elves are Humanoid (Elf), and so on. But with requirements written so more creatures could benefit from it, like doppelgangers, which are Monstrous Humanoid (shapechanger).
What this feat does is let you count yourself as a human whenever an archetype, feat, trait or prestige class requires you to be human. A few examples:
- Trait: Aspiring Bard (Human);
- Feat: Surge of Success (Human);
- Archetype: Imperious Bloodline (Sorcerer/Human);
- Spell: Guardian Monument.
- There are no Prestige Class that requires you to be human at this point, the closest being Furious Guardian;
While a Kitsune could be targeted by an Enlarge Person, for being a humanoid creature, a doppelganger could not, as he is a monstrous humanoid. This is related to the creature's type, and even if the feat did polymorph your character (which it doens't) it wouldn't work, as explained on this other question.
There are very few character options that change your creature type, like the capstone ability (20th level abilities) of monks.
But, whenever an effect would affect only humans (Named Bullet), or cause extra damage to humans (Bane), or ignore you if you are human, you would also be affected differently. But Charm Person still wouldn't affect a doppelganger, because it targets humanoids and not humans. Similarly, a lycanthrope's curse could affect a kitsune, but not a doppelganger.
This took some digging.
In order to qualify for Human Guise in the first place, you must:
a) Have the Change Shape ability
b) Have the shapechanger subtype
c) Must have as one of your forms (it doesn't matter if it's your true form a not) that of a human.
The Change Shape ability specifically says
This ability functions as a polymorph spell, the type of which is listed in the creature’s description,
Which means that it will ultimately depend on which Change Shape ability you have. In your example, you asked about the Transmutation Wizard and Oni Sorcerer versions- the Transmutation Wizard's version transforms you into a creature of the beast, magical beast (if you're high enough level) or elemental types. The Oni Sorcerer's version transforms you into a creature of the humanoid type. Further, the Master Metamorph's Change Shape ability is identical to the Transmutation Wizard's- which means that your mimic would not qualify for the feat with the Transmutation Wizard or Master Metamorph's abilities alone. The Oni Sorcerer does- and because its version specifically changes you into a humanoid, you would count as a humanoid (human) for purposes of the Human Guise feat.
It's entirely possible that a different combination would give you what you're looking for (which is presumably to be considered an aberration (human)), but for the examples above, if you can get the feat at all, yes, you'll be humanoid.
As one further note, since polymorph works identically to the spell alter self when giving you a human shape (that is, by making you a humanoid), you'll need an ability to turn human that doesn't rely on the Change Shape ability regardless.