Magic

Magic is a powerful, natural force across all the Planes of Existence. It can be accessed by anyone, even by those who are not naturally attuned to it. However, they can only perform certain magical rituals. Those who are naturally attuned to the magical forces are known as witches (females) and warlocks (males), collectively known as Magic Users or Spell Casters. Different societies have different names for the magically attuned.
Witches and warlocks are not the only ones that are naturally attuned to magic. Many other supernatural creatures, such as Vampires, Werewolves, and Paladins are also naturally attuned to Magic, but less so than Magic Users.
While magic is an unbelievably powerful force, it is not without limitations. For example, mortal magic is unable to truly resurrect the dead. The only way this can be done, is through a dark magic known as Necromancy. Even then, the resurrected do not return as they once were. They are now known as Revenants -- mindless husks of their former selves that are bound to carry out their Master's wishes (their Master being whoever brought them back).
It is believed that the Paladins possessed a way to truly resurrect the dead. However, their secrets have been lost to time, along with their order.
Magic, while in the hands of naturally attuned, is capable of performing amazing things. Some examples include, but not limited to, teleportation, levitation, conjuring, elemental manipulation, and divination. More powerful users are capable of even traveling through time, and to to other Planes of Existence. Some Covens restrict what types of magic they allow their members to use.
Magic Users are able to use magic to prolong their lifespans, sometimes indefinitely. While some use this to varying degrees, like keeping oneself young and beautiful (an Eternal Youth enchantment), other simply slow down the aging process (such as Winifred Braxton, who although she looks like a woman in her mid-50s, early-60s, she is in fact over 140 years old).
Magic Users also possess supernatural creatures known as Familiars. Familiars are a Magic User's teacher, starting from whenever their powers first present themselves (normally around puberty). The Familiar takes the form of an animal, and after a Binding Ritual, becomes connected to the Magic User, mentally. The Magic User that the Familiar is bound to, is the only one who can understand it. Familiars can take any animal form, but they cannot shapeshift, or perform any other form of magic. They also have their own personalities and quirks as well. The bond between Magic User and Familiar is forever. If the Magic User dies, the Familiar will fade from existence. A Familiar cannot be killed, however with enough effort, it can be hurt (because of how strong Familiars re, it takes a massive amount of power to make one lose consciousness).
Magic Users have the ability to harness and manipulate magic through the use of spells and rituals. By using such things, Magic Users can alter simple things such as prolonging their lives, to complicated things such as altering history.

Type

Natural