School of Magic (conceptual)
School of magic is a term for a characteristic of a spell, that refers to one of the four basic elements: air, earth, fire and water. All spells belong to one of the four schools of magic, with exceptions of magic arrow and visions that both belong to all schools. School of magic is closely in a close interaction with air, earth, fire and water magic secondary skills, which each strengthens the effects of the spells belonging to school of the same name.
Heroes without expertise in magic secondary skills, may cast a school's spells at normal level (resulting in the same effect as the basic level spell). Increased expertise allows for spells to be cast at the basic, advanced and expert levels. Heroes holding expertise in a school's secondary skill cast spells from a school at a reduced cost. This cost reduction is the same regardless of whether a hero holds the skill at basic, advanced, or expert level.
Note: There is also an adventure map location called School of Magic.