Emblem of the Celestial College.
Known as the Blue Wind of Magic, Azyr is said to be a manifestation of the Aethyr’s reflection of inspiration and that which is out of reach. The magic of this Wind is based upon knowledge of the unknowable and the manipulation of the skies. This Lore of the Heavens (also known as Astromancy) is practiced by Magisters of the Celestial Order to divine the future and pluck the strands of fate.
Azyr has few temporal boundaries and supposedly reaches into all the possible futures as readily as it floats across physical distances. After passing into the mortal realm, Azyr is said to be drawn into the upper portions of the heavens, becoming a haze of eerie cloud, visible only to those who posses witchsight (the ability to actually see the Winds of Magic). This association with the sky gives Celestial Wizards their power over Storms, flight, and mighty hurricanes. As the Blue Wind blows from the timeless realms of the Aethyr across the distant sky, it supposedly appears as a clouded window through which Azyr’s Magisters can predict certain events. It apparently can be sensed by the manner in which the permanent celestial bodies are distorted by the drifting cloud of Azyr’s impermanent and temporally distorting blue light.
The magic of Azyr leads its practitioners to become dreamy and unearthly, with a calm, comparative demeanour. These gentle effects may lead some to believe that the Blue Wind is an easy thing to master—not so, for one glance into the eyes of a Celestial Wizard reveals the burning power of Azyr and the terrible foresight it brings. It is this foreknowledge that is the true test of Astromancy, for if you look into the future you must live with what you see.
References
Warhammer Fantasy RPG 2nd ED -- Realms of Sorcery (pg. 32-33)