Also I think it is possible to critical miss and hurt yourself? I'm pretty sure this happened to me when I was trying to cast that poison beam spell and knocked myself unconscious?

Did anyone every play Rolemaster? You only did most of your damage through high rolls, and you had to look at a big chart telling you how well or how poorly you succeeded. So a normal yet hostile squirrel who made a good roll could eviscerate a fully armored player or the player could get such a massively bad roll they could fall over and impale themselves on a fork. It was awesome. xD