He shrugs. "Okay. What's one of those? Is it the thing you need to have to do the magic that makes gemstones?"
And Joy goes back to reading his increasingly large stack of books. (He keeps finding new things to look up!)
And... cast.
There is an enormous puff of faintly glittery red smoke. Blueberry squints into the cloud, then clears it away with a little subtle telekinesis.
A beige mammalian biped who is wearing clothes and has red eyes and appears to have been sitting before he was violently removed from his chair falls to the floor. "Ack!"
"That is because I'm not a treatise," she says reasonably. "I'm a unicorn. And I was trying to bring back a dragon who disappeared a little while ago, but the spell I'm using has trouble distinguishing people except by broad obvious categories like species... maybe it got confused some other way. Do you know anything about a green and purple dragon suddenly appearing somewhere near wherever you just were? He's about this tall," she floats a book to a Joy-ish height to illustrate, because even if she stood on tip-hoof she'd be much too short to gesture it herself, "and his name is Joy and he's very friendly and helpful."
"I'd figured he was messing with tasteless illusions. I'm a dragon, I'm just not shaped like one right now."
"Oh, that makes sense. Well, it shouldn't be very hard to put you back now that I've got you... you're definitely the only dragon-like creature in Ponyville right now. Do you want me to do that? I'd just have to reverse a few things and then check my work, it won't take long. But then I guess you should tell Joy to go somewhere there aren't any dragon-like creatures for a size-of-this-roomish distance anywhere around him, before I try again."
"From my perspective, Joy disappeared mysteriously a little while ago and I went and looked up some spells until I found one that told me where he went, sort of, and then I went and looked up some more spells until I found one that could get him back. But it isn't very good, so it accidentally got you instead."
"Equestria! Ponyville specifically. The Ponyville public library, even more specifically."