"You did magic on purpose by singing without knowing any spells you didn't make up? Sounds like your affinity might be singing, or writing spells, or writing song-spells which would be really cool--affinity is a thing every wizard has, that makes it easier and more affective to do magic that ties into their affinity in some way. Wilbur's is thread, we haven't figured mine out yet, it wouldn't be at all weird for you not to know yours."

"Oh, if it's singing that would be really cool... how do I learn magic songs, is there a magic songs class -"

"Nnnno, not really. You can ask the void for them though."

"The void."

"In your room."

"The black wall behind the desk? Will sing to me?"

"--No, no, it'll dispense papers with spells on them."

"Oh. With sheet music?"

"I think so? Nobody Mum asked had got any song-spells that way, most of them are spoken."

"Okay. So I just... need a song to kill monsters?"

"...It's way more complicated than that. There are spells to kill things, but a spell has an amount of strength, and costs an amount of mana, and you need to have enough mana to fight or flee everything that comes after you. And some mals are insubstantial and a crushing spell won't do anything against them, and--you won't run into a maw-mouth before graduation, but there are, like, two times ever that people've managed to kill those."

"So... where does mana come from then."

"Effort. You build mana by exercising or doing crafts or getting out of bed even though you're sick or or slogging up flights of stairs or whatever. How much mana you build comes from how effortful it is, not what you physically do."

"Doing crafts?"

"Not the kind that you can do without even paying attention," she clarifies. "But I have a crochet hook and if I'm crocheting something and it's very finicky and I have to stop and rip out half of what I've done and curse about it every so often, I can get mana out of that."

"...are you going to crochet my hair?"

"Nah, human hair's finicky and wizard hair's scarce; Wilbur'll work it into something that's mostly silk."

"I guess I can do jumping jacks if I'm going to need to do magic every day. Till I can get like a sewing kit and fabric to make some... not... pajamas."

"There's workshops that have stuff but you need to be careful to make sure the supply cabinets don't have mals in them."

"Do classes start, like, today, or later...?"

"Tomorrow."

"What... time is it here, there's no windows."

"I'm not sure exactly, but evening sometime. Graduation in the morning and induction in the evening."

"And my schedule will be like, spat out of the sheet music void by the time I get back or something? Okay. Is there like paper somewhere I can use to tell my family I'm at Spooky Hogwarts, where's a mailbox...?"

"There isn't one. Any connection with the outside world is a way a mal can come in. Letters come in with the freshmen and if you can bribe a senior enough they'll bring a message to your family if they survive graduation, in a year."