Magicians are Humans who obtained an Art of any kind through witnessing or suffering a tragedy in their lives. The term Magician may mean Wizard or Witch.
For an unknown reason during the Time of Downfall, a Human accidentally got a Payment Art after his/her spouse was killed in front of him/her. There were several experiments done by the scientists in an attempt to create Magic again once the first person who obtained Art died. So many things had happened like wars and atomic bombing, leaving the world into ruins. An unknown object exploded and nobody on this world knew what happened. Years after the great explosion, Humans started getting a kind of Magic they called "Art."
Most Magicians were once normal living Humans until a particular event changes their lives. However, Humans view Magicians as beings far different from them and "selfless killers who gained the 'license to kill' after a dramatic moment." This is true for some of them because it really depends on what had happened to them.
Magicians usually care only about themselves and view the world as some rotting place. Many of them don't have fears anymore while some fear about everything. Their personalities vary but all of them rarely feel joy and guilt.
Art is the main ability of a Magician aside from their Mastery. Most and almost all of them don't feel the need to practice their Art even though it helps a bit. They dislike practicing it because some of them have some kind of payment once using it. A Magician's pupils turn pitch black when he/she use his/her Art.
A Magician's Mastery is the spell or ability they had learned and mastered. However, some Magicians had learned a number and use them but didn't master any.