I'm very confused by Shadow Theft's targeting. Shadow Theft, for reference, is on page 80 of White Treatises. I'm trying to figure out if you need an initial arcane link, and thus you simply "target" casting on the arcane link. If not, then do you have to have the target within sight? Does their shadow have to be cast upon the crystal inside the cage? Rather do you just name a subject, like Mnemon, First Among Equals?

Thanks!