There are a few sources of magic available to mortals on Tyar. Broadly speaking these are bestowed, external, or personal.
Bestowed magic consists those powers granted from another. This is the magic available to most clerics and warlocks. A bestowed practitioner’s powers are rather steady, but if they lose access to their benefactor then they might find themselves cut off from their powers. Other classes with subclasses that get their power from another entity are also bestowed practitioners.
External magic is when the practitioner manipulates outside energies without channeling the power of another being. Most druids and wizards work with ley energy on Tyar, where sorcerers can access the energy seeping through unseen portals all over Tyar. The higher the concentration of energy along a ley line where a wizard or druid are at the more potent their spells are. The greater number or strength of connections to other planes in the vicinity the greater a sorcerer’s power becomes. Other classes with subclasses capable of manipulating magic are usually external practitioners if their power is not granted by another being. The method of that external manipulation can vary from subclass to subclass. Even in the three classes listed a subclass may change how the class accesses magic on Tyar.
Personal magic is the least common form of mortal magic. Personal magic is typically the most draining. A monk’s ki expenditure is one such example. Many Mystics also use personal power. Any class can swing to personal magic, but it is usually more taxing to do so. The practitioner’s magical power does not wax and wane in relation to any external source or personal connection with another being. It does however depend on the individual’s personal well being and fitness.