Another one: Scout Drones. These have the same issue that the clockwork avians had, which is that they're just suddenly ON you, with little you can do about it. Unlike the Avians though, these guys are even worse in outdoor areas, because they have the super-irritating tendancy to drop from above, whereas the avians will always come from the sides.
Also, Mirror Cubes, these guys seem absolutely unhittable..... I really dont know what to do about them, as the only thing that can hit them is certain ammo spells. Other than that, the ONLY way to defeat these is to stand there, get hit, and fire at them when they hit you. Nothing else touches them.
Eels: Way, way too strong. The layout of most water areas that contain these mean that the only way to even hit them is to get close..... and you absolutely cannot do that or you WILL get hit. Even from a good angle though, it's hard enough to even damage them, as their attack just shuts down most of your spells entirely, and like the scorpions, they fire it every 2 seconds. These are at their worst in the swamp areas.
Crag Spitters: I'd say, slow down the firing rate on these guys. They're like the pigeons, except super difficult to hit with anything. There's alot of situations where the only solution is wasting an ammo spell just because you cant get anywhere near them, and no spells can either move at an angle that will hit them, or break through their attacks.
I forget the name of this one, but it's like a huge robotic.... uh.... snail? It's the one that has to be beaten with it's own missile. These guys are incredibly easy to kill.... probably one of the easiest in the game, and I get the impression that they arent supposed to be. It's really really easy to get their missile to just instantly smack the floor right in front of them, and then they just burst after that one hit.