Editing The Castle:Keep on the Borderlands (section)

===Dweomer ===
Sorcerers are lone individuals. There are no wizardly Universities or covens. Wizards live alone, taking occasional apprentices, and are feared and revered by ordinary people. They are not common. The art of Dweomercraft is a long and demanding skill to learn, taking years to grasp the basics and decades to master even one Art. It is commonly believed that most Wizards know the secrets of extending their lives, and many are said to be hundreds of years old as this is the only way they can learn enough of the Art to be truly powerful. Some Wizards seek patronage with Lords or Kings, offering their services in return for sanctuary and funding to further their arcane studies. 

Dweomercraft is a dangerous art. Many say that it was the Magus, Lord of Lies who first taught man the Thirteen Sigils and the Ninety Nine Words of Lore, and it was one of his darkest tricks. It is said that every time a Wizard calls upon the Arcane lore to bend the world to his Will, he risks his immortal soul. 

Warhammer 2nd Ed has quite a good mechanic to make magic risky.