Okay, so let's talk Laundry, and why Fern's choice (despite Serie's objections) is literally the greatest choice she could possibly make.

Do you know what the greatest invention in the history of mankind is behind the discovery of antibiotics? The washing machine (great video presentation on the topic). Not a joke. It is the single-most transformative invention of human culture. It took a chore that nearly an entire day's worth of heavy labor with middling results by one member of the household (or hired-out) to a task performed simultaneously with...literally whatever else you want to do with that time. Cleaner results, less damaging to clothing and skin, fewer harsh chemicals, and a whole host of other benefits.

Fern chose to learn the most practical spell ever, one that is stunningly revolutionary for the time period and setting they're in.

Of course it is from the age of myth. When magic was in abundance, people/elves must have used spells for anything and everything. Then some manner of regression across the world occurred (probably due to the demons), and the world is slowly stepping back up thanks to the steady and inexorable innovation of mankind.

It also follows the assertion that Frieren and Flamme are right in their discussions with Serie. The era of war is winding down. Fern is someone who values magic used in practical ways rather than in destruction or a cycle of revenge.

Quote Originally Posted by MFauli View Post
Btw how does spell-learning even work? Do they receive "grimoires" aka spells on paper, activate them like in a video game, and they grimoire vanishes and they got the spell? Otherwise, why not just teach others the spell?
Quote Originally Posted by Buffalobiian View Post
You read it and remember it.

You don't go around teaching it because you might like the exclusivity and you're also not a charity.
The anime doesn't explain it, and the shot of Serie handing Fern a grimoire is deeply misleading.

Serie knows all the spells because she's old as hell. The point of her boon is that she is able to grant people spells that would take actual decades to learn no matter how skilled they are. Spells that humans would die from old age before they mastered them, but the elves and demons have the liberty of time to learn. It's why mages like Denken go to her to take the exam rather than live out their days as the strongest Imperial Mage.

I'm not going to spoil the details in case they do every actually cover it in an eventual sequel series.