Magic
From the original Book of Lore entry: Magic, aka The Arcane Arts, is a powerful force that weaves its way through the lands. Most Wizards came into the world already specializing in a form of magic, such as hydromancers, pyromancers, and necromancers. Some conduct their wizardry through magical items and staves, and some Wizards don't seem to know any magic at all.
Magical talent is varied across Wizards- from hilariously amateur, to perilously threatening. Some use magic for virtuous altruism, and some for appalling cataclysm. The minds of the most powerful magic users often border on sanity, absurdity, mania and derangement, for there seems to be a trade-off every magic user must confront: Mastery of the Arcane Arts often comes at the cost of one's humanity.
How magic came into this world is a question of serious inquiry, but one thing is certain, it is a dominant force in the world, and colors all aspects of daily life, culture, and politics.