Nirth_90: While my opinions on manual and automation goes as a mix I still liked it. However I would have preferred the combat to be turn based.
I think the key is some exercise, in the beginning it's annoying but after a while it should go with ease. Try to save before a lot of enemies where you have the spells ready then reload and try different things to understand the game mechanics so timing will be easier. It also could help to have a decent mouse, I can see this becoming a huge issue if you're not comfortable with your mice or simply just bad.
Musashi1596: To be honest I am both using a laptop touch pad and inexperienced in fast paced PC games, but casting spells quickly was never really much of an issue when the game was running smoothly. When the framerate dropped a little though, which it did somewhat often for me, it became very difficult to cast spells properly because it didn't register your input consistently. And when you're using two mages, it can be a little frustrating.
I forgot about framerates but I always assume people try their best to keep it at a reliable speed. I only played with one mage so I can see the issue while playing with two or more, at least if you are meeting a lot of enemies so you have to repeatedly press the runes and attack.
I wonder if it's possible to play as three or four mages, that could be an interesting challenge. :)