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.
Famulus:
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?