I just saw Stradivarius mentioned just now and I realised I'd never even seen this attack on hard, so I tried it out and found this one. It might be worth noting this behaviour is still present, but slightly different on the other difficulties (I only tested easy and it gave me a different kind of defensive shot) although from what I can tell it isn't necessary on anything but hard mode since this attack changes so drastically between difficulties.
I think I'll go ahead and add this to the wiki myself, although I guess I'll add it here too anyway. If it's worth adding the other difficulty behaviours since they seem to be different to the rings on hard mode i can add them too. I still haven't seen the normal/lunatic cards yet.
* No 51 神弦「ストラディヴァリウス」 Spirit Strings "Stradivarius"
* Owner: Lunasa Prismriver
* Stage: 4
* Difficulty: Hard
* Possible spellcard cheat comment: The attack is designed to give little time to react so bullets are spawning close to the bottom of the screen far away from Lunasa.
* Behavior comment: Fires rings of bullets when you get too close.