The Patchwork Kingdom
All magic originates from a place outside of Here and at a different time than Now. The Patchwork Kingdom is a place of strange uncontainable energy that twists and bends the fabric of reality. It is a place of monsters that defy imagination and are often hungry for the flesh and souls of those who dare to peek into their place.
Some say that the dungeons of the Underworld are places where the Kingdom has pushed through and into this world. Some speculate that the demons that wander the terrible changing landscape are the source of all the ills in the world.
One thing that is known, though, is that the Patchwork Kingdom is where spells originate. If they are born, crafted, discovered things from an age long gone, or manifestations of desire and intent is continuously argued over by those that care about such matters.
What A Spell Is and Is Not
A spell is not a universal formula that can be copied from a text, memorized by a clever fellow, then cast in an identical manner by each and every wizard, sorcerer, and mage. Spells are patterns of mind-bending energy from the Patchwork Kingdom. They are manifestations of will and well outside the bounds of mortal reality. Spells are supernatural, some are living (unliving), and some are sentient.
Wizards are constantly treading on the edges of the Patchwork Kingdom - finding weak spots between that place of unrelenting power and the real world. They dig up clues, find hints, and in their nightly dreams or from waking fevered sessions of consciousness altering tinctures, potions, and herbs they eventually find a spell.
Each spell is personal and aligned to the sorcerer who birthed it. They hold it trapped in their mind and eventually release it into the world. Once cast, the sorcerer can feel the pattern burnt into their veins and each casting becomes easier than the last.
Spell cannot be taught, but they can be stolen.
Spell Books: Grimoires of Dark Passion
A mage will guard his spell book with his life. If another mage happens upon his dark grimoire and manages to decipher the cryptic writings, they can attempt to take ownership of the spell. The mage who first brought it into this world will feel an acute loss that is often so traumatic as to outright kill them. The spell's new parent and master may now wield it fully.
An adept's book of spells is also a catalogue of their research and adventures and pacts. This information can be used by the unscrupulous to do all manner of terrible things to the adept who lost the book and those who he has written down as friend, ally, thrall, or slave.
Hoola the Shadow Mage, the Adepts of Hate, and Caine the Lord of Uncertainty all have uncommon totems and therefore particularly uncommon magic. All spells that a caster finds will be channeled through their totem, the metaphor helping to ground the otherwise untenable insanity.
Specific totems are left up to player discretion and GM approval. Totems should be in line with the play style of the character. A Mouse Wizard isn't going to be blasting everyone with great balls of fire, nor will Julex the Eternal Bear tend to do a lot of stealthy sneaking about. Failure to work within your totem aspect will cause problems (like EP or Karma hits).
All wizards have the potential to create magic items - things imbued with the power of spells. Doing so can take a terrible toll on the wizard, so only the most powerful or desperate will do so. Most magic items are temporary - eventually the spell contained within will escape or be destroyed slice by slice. Only the rarest of items are forever.
Holding the physical manifestation of a spell has consequences as well, especially for those not used to the arcane power of the Kingdom. Nearly all magic items that have more than a single use (such as potions, powders, or scrolls) have some backlash associated them.
For example, the legendary blade Moonbeam was (is?) a short sword made of hard silver that could attack with the speed and power beyond that which a normal man could muster. Unfortunately for those that choose to wield it they are filled with an unbridled anger that appears when they themselves take damage. At this point, friend and foe are equally targets until the blood lust is sated.
Discovering New Spells
For example, Calix the Phoenix gets a new spell. He rolls 1d1000 twice with results of 442 and 839. Those two words are "infallible" and "snow". After thinking a bit the player determines that Calix has the ability to cast a spell that will causes a flurry of ashes (phoenix fire results in ashes which are like snow) that will blind his enemy allowing for an infallible escape or attack. The spell is named Calix's Infallible Ashes of the Phoenix.
When determining the specific spell effects from a games mechanic standpoint, look at other spells of the same level and work out some details and a spell point schedule. If this were a 6th level spell for Mr. Calix, it would seem to line up nicely with "Inflict Temporary Blindness" - so use those spell stats for simplicity.
You can grab the Spell Inspiration guide I put together from this link.