Digital Signal Processing by Proakis and Manolakis

The Laundry Files by Charles Stross are rather good. It's a Cthulhu Mythos like world, seen through the lens of espionage, bureaucracy, and computer science. The magic starts off fairly low key, but as the books progress it becomes a bigger and bigger component of the characters. Human sacrifice and the maddening effects of magic are fairly consistent themes.

DragonLance chronicles trilogy, followed by Dragonlance Legends trilogy. It features a superb character arc with a dark magic user that arises out of an amalgamation of other wondrous character arcs, much like the DnD campaign of the same name.

The Power of Subconscious Mind by Joseph Murphy

Not sure how easy it is to get old comic books now that digital is an option but there was a whole doctor strange arc where he sorta got tainted and had to increasingly rely on dark magic. To me it was on the level of iron mans armor wars and I really wish both had been used with the movie arcs.