Howdy guys, and sorry if this is obvious, but I've got to ask because it's bugging me that my spells miss so often. Is spell chance to hit or miss based on intelligence, attack rating, something else, or what?

My instinctual thought would be intellect because spells often say that they do up to that in damage, and thus it sounds like the damage is a result of difference between offense roll and defense roll, as other attack work to my understanding, but I often attack targets with 0 armor with a 20 int channeler who misses, so I think I'm missing something.

Can anybody tell me how it works? Thanks in advance.