Actually, if you want to pull reference from it, there's actually even a Craft Magic Tattoo feat in DnD. It covers usage, power of the spell inscribed, price, and brings up another potential matter - multiple aetheric tattoos.
Size and complexity of the tattoo aside, would using one's own body as a medium cause issue if you have more than one? Also, what if the person has a natural aetheric ability - such as the ability to sense aether... or the Echo? Would these tattoos need to be modified to account for that?
Size and complexity of the tattoo aside, would using one's own body as a medium cause issue if you have more than one? Also, what if the person has a natural aetheric ability - such as the ability to sense aether... or the Echo? Would these tattoos need to be modified to account for that?