Pyromancy is one of the forms of magic of Mundus. It stems from the use of one's own internal flame to produce magical effects.
Pyromancy occurs about evenly in all human populations, but it varies greatly among the Din. Zells have the lowest count, to the point that it is still popularly believed that they simply can't perform pyromancy.
Inside every living creature, there is a Flame. This is the spark of life. A sort of animal soul that burns and consumes. It wants simple things, sex, food, warmth. In humans, who have a higher spirit, the Flame is not in direct control, but is subdued and chained.
Because of this, human Flame is much, much more hungry than it is in animals who allow it to rule their every action. It is ravenous, and willing to trade anything in return for a taste of the outside world. Pyromancers are people who, wisely or no, break down the seal between them and the Flame, and trade with it. The Fire is powerful, it is the primal element of life, and given fuel, it can do great and terrible things.
But what does the Flame want? It doesn't want gold. It doesn't want praise. It doesn't want something petty like frankensense or burnt cloves. The Flame wants what it has been denied. It wants to live. It wants experiences, feelings, and memories.
So, a Pyromancer feeds the Flame bits of his own personality, burning away memories of times past, good times and bad times, friendships, emotional attachments, records of experiences, and whatever else he has, in return for the power to control this primal life-force.
Pyromancers can influence living things. They can heal, or hideously harm, dominate the mind or the body, create and manipulate fire, and communicate with the fires of other living things, even to the point of asking them questions after death. (The fire, you understand, never truly leaves, it just changes hands as a body decays or is eaten.)