Rules for tattoos as enchanted items are in HoH:MC and make perfect sense. But what arts would you need to affect tattoos as spells?
If I wanted to turn a sword into a tattoo, I'd obviously need Terram for the sword, and lets say the dye for the tattoo is mineral based so terram for that, would I also need corpus to integrate it to the human body? And what makes common tattoo inks? In period?
Muto Terram should be able to do this with some mags for complexity. A little while ago I asked about flattening an object to 2d and came out with this spell:
Flatten Miscellanea to Art
Muto Terram 20, R: Touch, D: Sun, T: Ind
The object touched is converted into a small two dimensional image of itself for the duration of the spell.
Casting requisites are required for the object when cast.
(Base 4 to change dirt so that it's highly unnatural as two dimensional, Touch +1, Sun +2, secondary sub-effect to shrink +1)
Once it's flat you might need a sub effect to make it stay on your skin as a tattoo, a small ReIm effect?
PeCo has a guideline to destroy a property of someone such as their weight or solidity. A dimension could drop in the same ballpark.
Philosophically, does a 3D object converted to 2D become an image? I'd be tempted to say that in the Arsmagica paradigm, it is henceforth affected by both Terram & Imaginem.
PeTe with a base of 40 and a duration would work
MuTe(Im) to turn it into a 2D also works. Don't think you need to rego it unless it is done in two phases where you turn the sword 2D and then try to find someone to tattoo it to them.
Would make for a cool ritual where you turn things into ink that can be summoned by the tattooed at will for the duration of the "Tattoo". Duration tattoo would require a bit of research to work...
In Societas, under the Jerbiton chapter, there is whole section on illusion, including a spell converting a objet into its 2D variant (for perfect drawing in a book). It could be used as a base to temporarily convert item in 2D variants, easy to carry around.
I remember seeing a topic on doing the same with soldiers' companies to move armies easily and discreetly. I don't know if a living being can be turn into a 2D objet and brought back. What happenend when they are in a 2D shape ? do they age ? do they feel hunger ? do they need sleep ?
Using the Muto Corpus guidelines, it would be a MuCo 30: turn a human into an insubstantial objet (Imaginem requisite instead of Auram), +1 for touch, +2 for sun = MuCo(Im) 45. For a moon duration, it becomes a ritual (level 50). As per Silent Vigil, you do not need food or drink, though you do age.
I guess a ring version would make a perfect prison as the prisoner cannot act at all.
I would think you would want MuTe(Co,Im) or MuTe(Co) since you are making the object part of the person. (Change Corpus to Animal if the tattoo is on an animal.) Same idea as The Silent Vigil's requisite.
Why is that?
Level 50 need not be a ritual, ArM5, p. 114 only states that
Henna might be an option for temporary "tattoos", particularly for Moon Duration effects, if the Order has knowledge of it.
The ones active in North Africa and possibly southern Iberia, probably. Have you had a look in Between Sand and Sea?
The rest of the Order, less likely.
My mistake. So then yes, you can have it at moon duration without making it a ritual. Much more useful in this case, only a little bit of warping.