What level is this unfamiliar spell?

This has crossed my mind before, but the ballad of the siege-sheep reminded me of it.  What level would you assign the following spell to?  I'm aware there's math for it in the PC, which I'll come to, but I'm equally interested in first impressions.


Cast upon a mage's own familiar, this spell transforms it into the form of a human for up to 24 hours, most commonly to act as an assistant in magic research, or to otherwise make full use of proficiencies reliant on opposable thumbs, such as healing.  Although fully competent when acting within their proficiencies, the form is otherwise strange to them; they attack as 0-level humans while transformed, and the GM is encouraged to remember they lack both general proficiencies and the Adventuring proficiency.  They converse as normal when talking to their master, but their speech is stilted and limited when talking to other humans, even in the languages they comprehend, except that they can always communicate concepts and directions appropriate to their proficiences.

Level:  ???

So, math for a Transmogrification spell:

Form of a living creature 35, new form's physical characteristics 10, I omit physical attacks and special abilities and call it 45.

Form limited to particular type, x0.75=33.75

Form limited to caster level and 2x target level, x0.75=25.3125 (I'll come back to this)

Target 1 living creature, x1, no change.

Range touch, x0.6=15.1875

Target may cancel spell at will, x1.3=19.74375

Duration, where it all falls apart.  I can have an hour at x1, but for a research assistant I should really pay for the whole day, which is x3 and brings me to 59.23125, and a sixth level spell.

Which feels way too high.  And let me say I'm all for the GM just making a call here and moving on, so it's not that I'm hanging up on following the rules to the letter.  But I'm also skeptical of sweetheart deals, and since it's my own baby I'm curious how other people would rule here.

The obvious angle of attack, even sticking close to the PC guidelines, is that "form limited to," 0.75 multiplier.  Because the form is half caster level (by hit points), or less than one hit die (by attack throw), but .75 is as low as the book goes.  .5 still only gets to 39.5/4th level.  I need a .25 "form limited" multiplier to get this spell to 2nd level, or a .3 multiplier for 3rd level.

I originally saw it as 2nd level, but I can see a case for 3rd:  by the book a mage needs to be fifth level to engage in research in the first place, and cancel at will makes it useful in the field as well.  What do you think?

Here is my take on it:

First, I don't think you need the 'physical characteristics' part. I take that to mean that the newly transformed creature gets the AC, hit dice, etc. of the new form; what you're going for is transforming a battlesheep into a battlesheep in human form, albeit with human speech, so you don't care about anything but form.

Second, add "Form limited to particular type of creature," since you'll only ever turn them into a human. That's x.75.

Third, add "attack throw required vs unwilling creatures" - you're not planning on using it on enemies, but it lowers it anyway.

All that is well within the rules, no bending required, and gets you a second level spell for 6 turns + 1 turn per level, or a full day for a 4th level spell. But, what the spell actually does is turn the creature into a human fighter of your level, not a 0th level one. Way better than you're asking for.

To bend the rules a bit, if you changed "Mental characteristics replaced by new form’s" to "Willing targets limited to level 0", you could keep the x0.2 multiplier (remove the x0.75 attack throw vs unwilling creatures and x0.75 form limited to caster level). Which results in 12.29, or a level 2 spell, or a level 1 spell for 12 turns.

Given that it can only target your familiar, I would happily allow the "Self" instead of "Touch" modifier. If the purpose is primarily research, I am willing to give up the "target may cancel at will" modifier. I'm also comfortable making the specific limitations (attack as 0 HD, stilted speech, etc) an ad-hoc 0.75x multiplier.

Doing that gets me to ~28.5 points, a 3rd level spell, which is fine at fulfilling the intended purpose and leaves room for breakthroughs to make a more powerful version if desired.