Ok, so since this first version was a bit over complex, I'll be winding it back a bit and starting with a much simpler system. From there, it can then be developed further if need be.
The other main thing is that I have avoided any terminology (as much as possible) as to how the "Influence" actually affects the characters; in regards to "madness" etc. It's just all about Embracing, or Resisting Diablo's "Influence".