Phantom Form?

[Minigiant]

Now the rules are very clear on this, a Phantom takes a Humanoid form.

Are there any implications for swapping forms to something else? e.g a Donkey

[Trokarr]

You may want to check out the Cavalier Ghost Rider archetype. This archetype allows you to gain a phantom steed that functions as a spiritualist's phantom in the form of a mount appropriate for a Cavalier. https://aonprd.com/ArchetypeDisplay.aspx?FixedName=Cavalier%20Ghost%20Rider

[Minigiant]

I have no intention of riding it

[Trokarr]

There is no requirement for you to ride the mount. I brought up the archetype as a legal way to get a phantom that is not in humanoid form. If you want a phantom horse (or donkey) that you never ride that’s entirely up to you.

[Minigiant]

I know but are there any rule implications or interactions that would effect the phantom differently because they are not in a humanoid form

[Azothath]

yes. Spells sometimes target creature Types and thus changing the type would affect what spells can target it. Changing creature Type was a major reason PF 'fixed' polymorphing thus lending credence to the concern. It brings a host of changes like movement, attacks, natural attacks, monster type or racial abilities like pounce, rake etc.

If you are homegaming to allow a somewhat frequent change I'd review the various polymorph spells.
Eidolons have various shapes but once a class chooses a form it stays that way. There are specific spells to affect eidolons, familiars, etc.

I'd suggest you post in Advice or Homebrew forums for implementation/design advice.

[Trokarr]

The phantom steeds type changes to animal but it remains a phantom not an animal companion. It’s stat block changes from that of a normal phantom (including type and number of attacks) but remains fixed and progresses normally as a phantom (mostly) and doesn’t really change beyond that. The animal “form” it takes is mostly cosmetic. Most effects that would normally affect a phantom would probably affect a phantom steed as well. That’s the way I read it anyway.