The only non-Collegiate authority the Grey Order is theoretically answerable to is the Emperor himself, but in effect this is not as clear cut as it would seem. ... Volans, the first Patriarch ... forbade that the Grey Order should ever sell their skills to aid the various political manoeuvrings of the Elector Counts and other governing bodies. Their goal was to oppose Chaos in all its forms, not to unduly influence the internal political struggles of the Empire. An Emperor could be forced to abdicate, or worse, may fall to Chaos and would then stop being an ally and become a potential enemy to the Empire.
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Shadowmancers can be found in the service of important officials, merchants, and nobles... Shadowmancers may only practice their spellcraft for the benefit of Imperial society and are expressly forbidden from using their magic for their own profit or solely for the political or financial profit of their patrons. ... Any breaches of the many strict rules laid down by the Order are prosecuted very harshly and vigorously.
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The Order of Shadows has killed or Pacified more of its members than any other of the Orders of Magic, and this is more of a reflection of the zero-tolerance of rule breaking and corruption within the Order rather than a demonstration of their Magisters' unworthiness.