Arcane Schools

A Wizard can choose to specialize in one school of magic, gaining additional spells and powers based on that school. This choice must be made at 1st level, and once made, it cannot be changed. A Wizard that does not select a school receives the universalist school instead.
A Wizard that chooses to specialize in one school of magic must select two other schools as their opposition schools, representing knowledge sacrificed in one area of arcane lore to gain mastery in another. A Wizard who prepares spells from his opposition schools must use two spell slots of that level to prepare the spell. For example, a Wizard with evocation as an opposition school must expend two of their available 3rd-level spell slots to prepare a Fireball. In addition, a specialist takes a –4 penalty on any skill checks made when crafting a magic item that has a spell from one of their opposition schools as a prerequisite. A universalist Wizard can prepare spells from any school without restriction.
Each arcane school gives the Wizard a number of school powers. In addition, specialist wizards receive an additional spell slot of each Spell Level they can cast, from 1st on up. Each day, a Wizard can prepare a spell from their specialty school in that slot. This spell must be in the Wizard’s spellbook. A Wizard can select a spell modified by a metamagic feat to prepare in their school slot, but it uses up a higher-level spell slot. Wizards with the universalist school do not receive a school slot.