You admit that you don't know much about runestones, and ask how powerful the inscribed spells can be.

Twilight Sparkle: "Quite powerful, in fact! They hold about as much magic as an average unicorn's horn. The main difference is that we unicorns channel spells using the magic flow from our body, while runestones release all of their contained magic at once when they are used.

Incidentally, runestones can backfire if you drop them by accident. As long as you're careful, though, they're valuable, since they don't drain magic like, say, enchantments do."

Moonflower: "Cool! So, what kinda spells can we get?"

Twilight Sparkle: "Any arcane spell that doesn't target the caster should work. If you're interested in browsing each magic school, I have a few dozen books you can borrow. Or, if you already have some kind of spell in mind, I'm confident I can help you find exactly what you're looking for."