The Magic System
What’s interesting about this is that it’s kind of in the middle between something more technical like Wheel of Time and something more mysterious and less explainable than Lord of the Rings. The rules it has are interesting, and overall I think David Eddings does a good job with it.
I also like how, midway through The Malloreon, he expands it a little. We see someone taken control of in ways similar to being compelled in Wheel of Time. We also see them find a way to heal someone from a poison by using a rare seed and the magic system to raise the plant, then heal the person. This kind of goes back to Wheel of Time and characters learning how to do something new or using the magic system in a different way.