Magic is going to be the most difficult hurdle to go through. It’s pretty different from what we have in D&D. I have not even thought yet about how to adapt it, only that Warlocks should be fine! The other casters... not so much.
In my world (whose name is in flux again!), magic comes from the souls of Mortals (that includes animals too -- anything with a soul born on the Mortal plane). Their souls house a spark of Creation, the infinite energy used by the Creators to build the universe. They have to harness this energy with a ‘Pattern’ to get magic; all the while opening the doors within that seal Creation.
There are four types of magic, tied to the Patterns through which Creation has to flow to make magic:
- Elementalism: this involves drawing in free floating magic in the world, the byproduct of ley lines and of the elemental gods (the Reiarchs); these particles are called rée or elements. There are six types of them: Light, Shadow, Water, Earth, Fire and Sky.
- Animism: this involves using one’s spirit (another part of the soul) to follow ley lines and connect to other people’s spirit to affect them. This can be in benevolent ways, such as calming distraught patients in clinics, soothing crying children, or in malevolent ways such as mind controlling people. This also includes the ability to manipulated one’s soul to the extant of moving it to other bodies, but this is high level stuff!
- Flux magic: this involves manipulating ley lines themselves by using one’s soul’s innate connection to the weave of lines (which are also called flux, hence the name). Ley lines scale from microscopic to galactic and permeate the world. Everything is connected and flux magic can make things more connected, less connected, but also strength the pull of ley lines on objects, effectively turning into telekinesis. This is generally the basis of magic but it has depth that is rarely sought out.
- Fey magic: this is the Warlock’s magic, it involves getting powers put into your soul by Fey deities. This always involves something in exchange, generally your soul -- they want the Creation within -- for a while or for eternity. Some may seek this out as a means to break the cycle of reincarnation should they be aware of it. Most of the time, it’s a matter of seeking more power.
In conclusion, I don’t know yet how this would play out in D&D 5e. Opening the doors of the soul sounds like some chi mechanic and I figure animism sounds like psionics. But I’m not sure about anything yet!