Here are a quick few thoughts on how magic is now working in the setting. I’m not throwing rules in with this yet, as I’m still working some of them out. This is more for flavour.
First, a word on elements of magic/nature.
The forces of elemental magic at work in the Old Crown, and indeed in the rest of the world revolve around two pure elements, Light and Dark.
All other elements are subordinate, seen as a mix of the two, with sentience and the element of Mind at the exact balance of between Light and Dark. Other balances produce the elements of Air, Earth, Water and Fire, since scholarly study shows many similarities between the elements at some fundamental level.
What this means for the Old Crown is most important for the magic users themselves.
The various Oathed orders all follow the different Ascended, and each Ascended is associated with Light, Dark, or Balance. These labels don’t necessarily infer goodness or badness; the Burned Man is and Ascendant of Light, the Storm of Balance, and the Black Lady of Dark.
An arcanist of the Old Crown will be schooled in various practical lessons, but will naturally gravitate toward some element that comes easiest to understanding, or manipulating. Many go on to learn other elements after their formal schooling, and the Archmagus of Raethmoor Academy is known to be a master of several.
Some arcanists find they are more strongly drawn to the elements of Light and Dark themselves, and some very few claim proficiency with Mind.
Witches and seawitches have an innate bond with the magical world. They feel an affiliation with the natural world from a young age, sometimes speaking to imaginary creatures only they can see (spirits), or else able to perform small feats of magic without any arcane training.
Many form a close companionship with an animal. Usually, this animal is blessed by an abundance of the element of Mind, much smarter than the rest of its species.
Some bond some part of their spirit to that of a nature spirit, carrying it with them wherever they go. Sometimes this is an elemental spirit instead, such as a fire or water elemental. Some fewer witches claim to have a bond to a Barrowight.
Next, souls and spirits.
All life has a soul, or a spirit. Some have no physical body, such as nature spirits, or the ghosts of the long dead, the Barrowights. Some elemental spirits do have a physical body, and these are called Daimon by most. They might be creatures with little in the way of a mind, residents of some distant existence in the heart of Dark itself.
Some stories persist of Daimon being born to witches bonded to elemental spirits, but most witches scoff at the idea.
The most dangerous Daimon are those with a strong connection to Light and Dark themselves.
Also, when any person creates an object, they put a part of their spirit into the task. If this is a meal, it rarely uses much of the spirit, but a more laboured process such as the creation of a piece of artwork, or a weapon, or an item with some magical purpose, will yield something else. Such Soulforged items gain something from their creation. Whilst not all spirited labour creates a true Soulforged item, when created they have a more awakened sentience themselves.
Tales abound of swords singing in the hands of their wielders, but more common is the kettle that boils when left in the sunshine or fine clothes that remain dry in the fiercest rain.
When an Ascended has a hand in making some item, it will generally absorb a part of their more powerful spirit, becoming Godforged in the process. The most famous Godforged items, like the Black Lady’s Crown of Thorn and Feather or the Masque’s Cloak of Falling Shadows have stories told about them across the known world, and are known to always be in the company of the god that forged them.
It is said that Soulforged items created by an Ascended before they become gods grow suddenly in power and become Godforged on their creator’s Ascension.
The process of giving a part of the soul for the creation of a Soulforged item is generally accepted to be the same process that bonds witches to spirits, though they receive something in return. Some believe the same process is used by the Fiend and his followers in the Undeath Curse, though only they would know if it is so.
It is also generally agreed that whilst the labour of love necessary to create such items can drain a person, leave them feeling particularly empty or vulnerable because of the effort of their spirit, over time they recover, and a person’s spirit cannot be destroyed in this way.
There’s probably more to magic that I’m forgetting, but the various bits on ritual and stuff aren’t that set in my mind yet, so I can work on those a bit first. Feel free to comment and give me some feedback!