How does undead anatomy work?

Question

Here is the description of the undead anatomy spell: Undead Anatomy

Here are the general rules about polymorph spells.

There are two points that are contradictory in these rules:

1. Which natural attacks do you obtain?

   • The spell says you get a bite attack and two claw/slam attacks, but what if you polymorph into something that has no mouth, do you still get the bite attack?
   • The generic text says you get the natural attacks of the creature you polymorph into, do you cumulate these with the bite+claws of the spell? (it sounds silly)

2. What exactly are the creatures you can polymorph into?

   General rules say you can't polymorph into a creature with a template, but the spell suggests as an example that you can polymorph into a zombie or a skeleton, without clearly indicating that it is an exception to the general rule.

   Can you polymorph into other simple templates such as a human-vampire or an elf-lich? Can you only use the archetypes that make a creature undead so you can be a gorilla-mummy but not a bodak-clockwork? In this case can you be a dwarf-zombie-lich?

Answer 1

On natural attacks

Despite seeming absurdity, the spell undead anatomy I et al. grants the natural attacks that the spell says it grants, and that means, no matter the form, a creature that's the subject of the spell gains the bite attack and either two claw attacks or two slam attacks. Is that weird and a gross simplification? Sure. But Pathfinder mostly succeeds in making reasonable many of the form-changing issues of its predecessor.

(That predecessor—Dungeons and Dragons 3.5—has form-changing rules that underwent so many changes that only the game's most dedicated scholars can determine how such effects work. Some folks—like me!—, rather than deal with the rafts of errata and frequent outright rewrites, just ban form-changing altogether in D&D 3.5 except in specific cases. But in Pathfinder there's no need for such a heavy hand.)

So while it is weird and a gross simplification and maybe sometimes dumb, the effect is also playable. Just getting those specific natural attacks—even when such attacks probably shouldn't be gained—from the spell undead anatomy I et al. instead of, for example, whatever natural attacks the creature actually has (or, anatomically, should have) means Pathfinder's monster designers needn't limit their monster designs. That is, if Paizo wanted to publish, for example, a 2 Hit Dice undead with 10 natural tentacle attacks, Paizo can and needn't worry some PC is going to change into that crazy form by casting the spell undead anatomy I et al. and get all those tentacle attacks.

On the assumed form

The spell undead anatomy I et al. is specific about transforming into undead and that includes in the spell's examples templates that transform a creature into a creature with the the type undead, like the template skeleton and zombie, contrary to the rules of the school of transmutation. Paizo threads from 2012, 2014, and 2015 lament the same lack of clarity on precisely what forms can be assumed by the spell undead anatomy I et al. that your question does. Currently, how deep the rabbit hole of what forms the spells allow one to assume goes is a GM's call. Does the spell allow a human to assume the form of a goblin bodak, a monkey skeleton, an oread lich, or a troll zombie, all of which are, as the spell requires, "vaguely humanoid shaped"? Maybe, and, while there doesn't seem to be anything particularly unbalancing or wrong with a GM ruling that those forms're okay, exactly what forms can be assumed is still a GM's ruling.

However, were I GM and wanted to make things easy on myself, I might make a house rule that the spell undead anatomy I et al., while allowing changing form into a form with a template, only allows changing form into a creature with only one template and that template must change a creature's type to undead.

Answer 2

Specific always trumps general, so the text of undead anatomy takes precendence over the general polymorph rules. Therefore the attacks you get, and the only attacks you get, are the bite/claw detailed in the spell. This functions regardless of the undead type you're mimicking - so even a vaguely humanoid undead missing arms gets some kind of attack equivalent to a claw and one missing a mouth gets some kind of attack equivalent to a bite. Feel free and 'reskin' and describe those attacks as whatever may make sense. If the undead creature you're simulating has other natural attacks, you don't get those.

You can polymorph into "any vaguely humanoid undead," which does include templates. A zombie, a wight, a vampire, a mummy... RAW, I suppose a "gorilla mummy" is legit but I certainly wouldn't allow that at my table, just adding on the undead part. Regardless, you can't change anything else about yourself or apply other templates. "Polymorph spells cannot be used to assume the form of a creature with a template or an advanced version of a creature." An obvious exception for the undead templates needs to be made but that doesn't mean you can add other templates like clockwork.

Answer 3

One key factor a lot of people are overlooking is that the spell requires as a material component "a piece of the creature whose form you plan to assume" By the very basics you at least need to find the creature you want to turn into.

Answer 4

Here's how I handle this spell as a GM. Undead Anatomy simply applies an undead template to your current form. That's it. The name of the spell helps support this as it gives you the "anatomy" of an undead. This is very different than all the other polymorph spells, but such is the way of magic in general, it breaks certain rules all the time. You want to be an undead troll? Go ahead, just cast Monstrous Physique II to turn into a troll and then cast Undead Anatomy and apply the template. This is the only time I allow two polymorph spells to take effect on a person since it's an odd duck anyway, but it works and stays fairly balanced by the spirit of the spell. Otherwise the spell is horribly broken by RAW.