It's a great question that I absolutely can't answer in 140 characters. In fact, I hit 1259 words when going in to the intricacies of what makes a mancer and other details of magic in Kavet in specific and the world of Castra in general, so I decided I needed a whole section of my site to answer them. Here goes:
The "Scholar Faolan" pages follow the research and interests of a fictional character from the world of Castra, home of the Mancer series. I encourage readers to post additional questions on these posts, or through my Twitter or Facebook pages. You will be able to find an introduction and an index of current posts here, or through the link in the site header.
About the Author:
Faolan of K’net is a Tamari scholar renowned for his travel journals and in-depth research into both the mundane and the mystical aspects of the Castrili World, spanning from the shores of Silmat to the isolated island of Kavet, from the icy Embracing Sea to the tropical waters of the First Royal House of the Osei.
Topic: The Mancers of Kavet
Part 1: What is a mancer?
What is a Mancer?
For those of us not native to Kavet, these so-called “mancers” seem to be a myth. They are not the witches and alchemists of Ilban, the fortune tellers and small magic users of Tamar, or the holy shamans of the Kordku. Compared to all these aforementioned magic users, the powers ascribed to these “mancers” seem beyond belief.
What are these powers?
One hears talk of mancers who can summon fire from bare stone, or cause deadly wounds with a thought. Some can supposedly draw lightning from a clear sky to strike against their enemies, or freeze the air in a man’s lungs with a glance. Others are rumored to have the power to raise the dead and possess the living, or even to funnel power from the worlds beyond in order to prolong their own life and power in this world indefinitely. Such claims seem hard to credit, but if they are anything less than true, why has the once-prosperous Kavet enacted such draconian laws to control them?
Whence come these powers?
It is hard to get a concrete answer to this question. To start, it seems there are at least four kinds of mancer-- Abyssumancers, Numenmancers, animamancers and necromancers-- and the answer is not the same for all of them. I have in my studies heard rumors of a fifth kind, a gressumancer, but I have not been able to confirm these tales as anything but speculation.
It seems clear that mancers of all kinds are born to human parents in the usual fashion, and develop their powers at some time later in their lives. This is where my research first hits a divergence, for some sources say these illicit sorcerers seek out this power; others say it may be “caught,” much like an illness, if the individual engages in certain dangerous acts; and other sources say this power is a curse thrust upon them through no error of their own.
The source of necromancers’ and animamancers’ powers is unclear, but Abyssumancers and Numenmancers have a connection to the Other realms: either the infernal Abyss, or the divine Numen, and to a particular denizen therein. It appears that Abyssi and Numini who bond to mancers gain strength through the connection, and perhaps the ability to manipulate- or even enter!- the mortal realm, which otherwise is barred to them. In exchange, their mancers gain the extraordinary magical powers previously mentioned.
Continued in Part Two! Upcoming questions on this topic: Is this bond willingly entered? What are the spawn?