The Screwtape Letters are a perfect depiction of ego at work, I recognized that devil the moment I read that first letter to Wormwood. It's more like a parable that uses religious beliefs to make a note of a part of our mind that shows those Screwtape characteristics. Aside from that collection though, I've read very little of CS Lewis' work.
We are powerful indeed, and if I could ever find a good time to get my video to upload, I wrote a song about how potent we really are.
Yes a dp, and I voted early! My curating instincts at work. ;)