"It's going to a Zev', right, not a Bell or an Adarin? Zevros could write it as long as it contains the basics, and if there's some of us around we can explain the sorts of things relevant to Bells and Adarins by mirrors."
"No. There's some - technological things, but I couldn't find any books or newspapers around, and it's not like I could turn on something through a scry."
"Well, there's two languages that have appeared as native languages among us more than once. Try those, and - include pictorial instructions for answering the mirror, in case that doesn't cut it?"
Turtle finishes the letter (in two languages, with expressive pictures) and then the mages collaborate and it arrives in the new Zev's house. Where it can't be missed.
"Uh," says Zane, looking at the mirror and the letter attached to it. He reads the letter.
And then he goes to get Cam, letter in hand.
Zane holds up the letter and mirror. "I got a thing. It's a confusing thing, I can barely read it. But uh - something about multiple versions of us? Also a magic mirror that got transported to my house?" Pause. "I'm extremely confused."