Orb of Sorcery

When the Elven Loremaster Teclis founded the Colleges of Magic, he gifted each Order with a handful of crystal orbs to help the fledgling wizards harness the Winds of Magic. Each orb is infused with the essence of one of the eight magical winds and it is even whispered that a portion of Teclis' own power is bound within every one of them. The Orbs of Aqshy are thus wreathed in searing flames and the Orbs of Chamon shift like flowing mercury between a golden sheen to polished silver and back again. The Orbs of Hysh radiate a blindingly white light so intense that they have been mistaken for miniature suns, whilst the Orbs of Azyr are as dark as deepest space, lit only by the swirling mass of constellations moving within it. Only the Patriarchs of the respective colleges can sanction their use. They are amongst the most powerful and treasured magical artefacts in the colleges' possession and the loss of any of them is a grievous blow to the Order in question.

Source

 * Warhammer Armies: The Empire (8th Edition)
 * pg. 52