Ok, kinda crackpot theory with no real evidence and zero research, but here it goes:
So in Sel, we see a lot different magic systems. There’s Elantrians, Dahkor monks, Blood Sealing, Soul Stamping, that other one I can’t remember the name of, and probably some others that we just haven’t read about. The Shards powering these systems are Dominion and Devotion, who were both splintered by Odium, forming the Dor. My thought is that not all of the splinters merged completely into one entity/the Dor, but that an imbalance of the two kinds of splinters merged together creating a general “Dor” that we see, but also creating specific magic systems based on the different concentrations of both Devotion and Dominion in one specific geological area.
Thoughts?