School of Air Magic
is about the characteristic of the spells. For the secondary skill, air magic.
School of air magic is one of the four schools of magic. Others are fire, earth and water. School of air magic is related secondary skill of the same name, which allows heroes' holding expertise in a school of air magic secondary skill cast spells at a reduced cost. This cost reduction is the same regardless of whether a hero holds the skill at basic, advanced, or expert level.