Ok, I just got a game over on SA stage 4 with Marisa-A.... IN PRACTICE MODE. Oh god, how do I suck so bad with that shot type, and why does Satori move too much on her second-last card.
Yeah, that 2nd to last is a bit annoying, you've just gotta remember to stream slowly, restream well in advance, and know that the dolls aim for you when they come in contact with the sides of the walls. Try to ignore actually killing satori as that might screw you up, at least, that's what I do. You'll probably come really close to timing it out unless you have a decent amount of power and make sure to unfocus when she stops above you etc. (and I mean really close, if you focus and just stream+restream the spell you can usually cap it within the last 5 or so seconds, and that's with something like 3 or 4 power.).
Edit: To add to what I said earlier, check out some WR replays, they use an awesome technique to do alot more damage and cap the spell fast, although I've never bothered to learn it myself, it's not that hard a technique to learn.