I don't want to decrease the number of missiles. The whole point of the spell was that you can hit a few targets for big damage, or a bunch of small fry to get them out of the way.

The restraints really aren't that much. The area of effect is a cone with a range of medium. So long as you remain within that cone, you can target foes freely. It's Force damage, so it overcomes DR by default. It's as magic missile, so there's no rolling to hit. I added the limit per target to keep it from becoming a kill-all-in-one-hit spell; the whole point is that it effects lots of targets. Be glad, it could be worse: on my first draft of the spell it got 10 missiles per level.

I have another variant of this in the works, so if I can get the kinks hammered out it would help.