Pretty cool but the challenge's all over the place.
The Diamond Mogul and the Avalanche spells I think are too easy, I mean it as they look more like Nonspells.
There's the first spell, the Lightning Snow, and some other nonspells that use the dark small pellets: these pellets unfortunately are really annoying in a bad way. That's because they're both blending with the dark backgrounds (yes even on nonspells they tend to be hard to keep track off) and they're also together with bright-colored bullets.
There's also the survival spell which I really didn't like at all. Even with the slowdown mechanic, the highly random nature of the pattern often makes it unfair and unjustifiably hard. I think different colors with the falling bullets and the piling ones could help greatly (for identifying which is falling and which is rising - especially when they overlap so often), and make either the falling bullets OR the piling ones have only one speed for all. And also Yukari's sprite hides bullets so that was one unforeseen curveball right in my gabber.
All of the rest however is pretty great and accessible. Especially liked the slaloming nonspells. The theming too is well done.
Now all it needs is a replay option, and good thing I've recorded my perfect run.
(Also yes I managed to No Miss No Slowdown after dying 100+ times in the survival spell, how could you tell?)