This world has evolved over the years and has pulled form many sources. I freely admit that but it has synergized into something different that allows for a huge variety of how magic cn be used.
a major influence is the ADnD magical system. with it's heirachy of spells. The way spells work is that they are weavings that have been pared down to be the most effiecint use of the energy to get the desired effect.. they can be memorized and locked in. for use for the day and will then reserve a certain portion of the mages power.
Another major influence is the fantasy books that emphasize the weaving of magic into effects that can't rightly be called spells. David Weber's serieis with Wencit of Rum and Bazhell Bahnakson.. and the wheel of time are examples of these. this will give the mage more felxibility but takes more raw power than the spells.
Most mages go for a blended approach. Impress a few favorite spells and keep a resorvior of power in reserve to weave as needed.
There are also numerous accounts of mages ho specialize. In water fire air ice etc. etc.. these are available here too but again with some sacrifice.. if you are an ice mage you are vulnerable to fire and can not cast fire spells, On the other hand they are masters of ice creating ice armor for themselves, slowing opponents with sudden chilling blinding opponents with sudden local snowstorms and many other things.
There has been another way developed to use magic with the reawakening of the goddess Charvor. Her followers are all warrior mages or rogue mages who excel in physical combat. Their magic is no longer spells of weavings so much as modes. It has been modified to work with their warrior skills.. Terri the sharpshooter has incredibly steady hands and the ability to visualize magically where her bullets will strike. The Knight Commander Dalton seems to be able to move faster and even sometimes anticipate attacks. Where and what variations this new form of magic will take is up to the players and their creativity.
the mages here are in many ways also fairly standard. The main differences in them and other mages is the fact that they must have a discipline.
the Discipline doesn't really change what magic they can use, but how they gather it.
The Disciplines are
Tantric- gather your magic through sex
Celibate- Self explanatory
Ritual- perform a ritual to gather your power
Meditational- Meditate to gather your power.
Oath-Take and hold oaths the more powerful you become the more oaths you must take on and the more stringent they must be.
Secret- see oath substitute secrets
Sacrificial- you sacrifice the lives of animals or other intelligent beings (those give more power ) (( basically an enemy of the empire usually ))