Thank you so much for the feedback! It's honestly all pretty on point. I think one of the big mistakes I made is that I simply did not budget enough time for playtesting. All of my balance calculations were done fairly hastily and last minute, and it shows! But, I do think I'm going to continue to polish this a bit more in the coming weeks as a personal project so hopefully I can get that a bit more under control.
Re: the fireball casters, there's a part of me that's glad that you hated them. I wanted them to be a nuisance, but not quiiiite as much as they ended up being, so I think a reduction to their health and speed would be quite good. Their ability to run off screen is entirely unintentional, too! I did a last minute change to the collisions because the melee guys would get stuck on them when they stood still, but I forgot to make sure they could still collide with the invisible boundries I had established after my changes. xD Aaah... what's that expression? 99 bugs in the code, 99 bugs in the code. Take one down, patch it around, 137 bugs in the code... ? xD