Make more monsters immune to magic missiles.

Magic missile damage depends solely on skill and not XL. (Perhaps realized by scaling its damage die size - d4 for Unskilled, d6 for Basic, d8 for Skilled, d12 for Expert.)

Magic missiles, and possibly other rays, stop at the first creature they hit and don’t continue to other creatures behind it. Possibly this should only happen on the first magic-resistant creature and “the missiles bounce off” (they clearly aren’t bouncing off in the same exact direction they were traveling before hitting the target, and the message implies they scatter harmlessly).