Creatures and their Combat Styles

[Dyshein]

I'm in the final stages of finishing/testing my mod, but now I'm in what I consider to be the most frustrating part; creating creatures, assigning them spells/combat styles, and getting them to ACTUALLY USE THOSE SPELLS. Now I understand how to edit combat styles, but what I don't understand is how to get creatures I make to cast the spells I give them on a consistent basis. Sometimes they end up casting one after another like a madman, other times they just stand there and do nothing like I haven't even added any spells to them. Even using attack styles from creatures that only cast spells doesn't seem to work sometimes, and other times isn't even needed. I just get so frustrated by the inconsistencies in creature AI. Has enough had alot of experience in creating creatures and AI for them, is there something I"m missing that would allow me to more effectively control how they use spells?