Blue mage doesn’t make sense as a beam, since you can invert/reverse it like a projectile.
I like to think that there are 3 types of tower attacks as well.
Bullets, anything that travels through the air and can be reflected or frozen midair (I’m counting cloaking as a freeze since the bullets stop midair).
Beams, nearly the same as bullet, but with a higher rate of fire and cannot be frozen (think machinegun fire, and you’ll still take a little damage if you cloak after they start shooting).
Burst, anything without a time lag between attack animations (think really fast bullet, hits the instant it’s fired).