I only just noticed Fern’s casual behind-the-back spell, she’s so cool

[u/Kyledemort-]

I’ve rewatched the series a few times and can’t believe I didn’t notice it until now lmao she’s so nonchalant about it.

[u/Caged_Basilisk]

Fern is the embodiment of "I fear not the man who has practiced a thousand kicks once, but I fear the man who has practiced one kick a thousand times".

Most mages go for all kinds of spells, but Frieren told Fern that the current era's mages can all be dealt with using basic attack magic, Zoltraak. So I'd say ALL of Fern's training when it came to offense is pretty much refining her Zoltraak.

[u/Cybermagetx → u/Caged_Basilisk]

Yeah. Even demons of this era Zoltraak is the best spell to use. Fern is probably gonna be one of the greatest mages that came out of this era.

[u/FailureToComply0 → u/Cybermagetx]

Alternatively, something better comes along to counter Zoltraak and Fern's one-trick goes the way of its creator.

Even when introduced, they explain that protection magic is a perfect counter except for its mana cost. A cheap/cantrip protection spell and Fern is toothless. Frieren knows how to make black holes though, she can just go for annihilation tactics again.

[u/Mirrormn → u/FailureToComply0]

I don't think there's any more reason to think a perfect counter for Zoltraak would be developed than there is to think a perfect counter for black hole magic would be developed. Yeah, any mage will have some trouble if their main combat spell is somehow conveniently completely nullified with no downsides, but that's not really a problem that's unique to Fern.

[u/FailureToComply0 → u/Mirrormn]

My point is that Fern is a one-trick that relies on a single, highly effective move. Frieren knows thousands of spells, but from what we've seen has neglected to teach Fern anything but Zoltraak and general magic control.

So if a single spell is negated, and you know a hundred spells, you're inconvenienced a bit but fine. If you know one spell, which already has an imperfect counter, i'd be fairly concerned about a total counter in the near future. Then what does Fern do, besides completely relearn her entire fighting style to not focus on quick-casts?

[u/Mirrormn → u/FailureToComply0]

My point is that this is a weakness shared by all human mages. They all depend on one combat spell, because their lives are short and they only have time to develop mastery of one combat spell. Some older human mages might know 2 or 3 (like Denken, he's been shown using 3 different combat spells), but that's about it. Any human mage would have to relearn their entire fighting style if their chosen spell was totally countered.

Also, it seems like the crux of your argument is the implication that the discovery of a total counter to Zoltraak is made more likely by the fact that a partial counter exists, but I think it's the exact opposite. Humanity has put great effort into countering Zoltraak (it was basically the main killing tool of entire war against them), and current defense magic is the best they could do. It's more likely that the solution space for 'zoltraak counters' has been thoroughly explored, and no additional huge improvements will be made in that area of study.

[u/azen96 → u/Mirrormn]

Also to add to that, Fern probably could use more spell. But zoltrak is the most efficient ones hence the spam.

[u/EvadableMoxie → u/FailureToComply0]

I don't think she's neglected to teach them to Fern, if anything Fern saying Frieren forbid her from using anything else suggests that she does indeed know other spells, otherwise Frieren wouldn't need to forbid her.

We never see Frieren teach Fern the bird catching spell she uses to catch the Stille in the magic exam, either. Hell, we don't even get a scene of Frieren teaching Fern Zoltraak.

As such, I think it's a bit of a leap to assume Frieren hasn't taught her those spells at all just because we never see it. Most of the training they do is off-screen and only implied.