Um... Since we're vaguely on the subject of Rin and my last spell, I may as well drop my ideas for what it should be like... Be warned that I suck at explaning these kind of things, so if it doesn't make sense, that's why.
Anyway... The spell starts with me and Rin in the center of the screen, but we very quickly move away from each other, mirroring each others movements whilst firing a massive barrage of lasers. At about the halfway mark, the two of us begin firing sparks in addition to the lasers. As the clock counts down towards the end of the spell, we move up to the top-center of the screen, float beside each other and fire out a gigantic spark that takes up most of the screen (all the while still firing out lasers). If at all possible, I think it would be pretty neat if the spark could stay on screen when the timer reaches zero and the screen slowly whites out.
Um... Yeah... So, uh, what do you think~?
I also had an idea for an earlier spellcard called Flower Sign "Abandoned Azalea of May", but the only real idea I had for that other than the name was that it would involve Ruro's "White Rose" danmaku, albeit recoloured black (somewhat fitting, seeing how a lot of people seem to forget that black roses don't actually exist and all)...