For reference I went and timed out all three cards:
Idling Wave,
Omoikane's Device,
Earth Light Ray. The latter was even done no-focus.
For Earth Light Ray, the circular waves of stars are completely static, so it gets much easier once you learn where those are. I typically think of it sort of like lanes divided by where the lasers roughly are, direct the aimed stars to one lane, and then dodge to the one next to it that's still closest to the center (you don't want to have the aimed stars going off to the side since avoiding that requires fast micrododging, as shown in the replay). The problem is that the lasers aren't static; as far as I can tell they're random, so you may get luckscrewed on this one.
Idling Wave is Reisen's hardest spellcard. I usually bomb it during serious 1CC attempts, to be honest. If you want to capture it, pick a corner (I use lower right), rush there when the bullets dispel, then dodge the ring horizontal to your corner, then vertical, then diagonal. The next wave should start spreading while you're in the process of dodging the diagonal ring, so you get to the center and repeat the process. It helps a little to know there's a safespot a little above the "Enemy" marker for the first wave only, so you only have to dodge 2 rings instead of 3 on that one.
The trick to Omoikane's Device is to stay close to the familiar. Counterintuitive, perhaps, but if you get too far away you need to go a lot faster through the pellets, and since the gaps are fairly small that makes it a lot more likely that you'll make a mistake.
