This is the Violet Vanguard Guild.
The Violet Vanguard was orriginally just a childhood concept while Nickans and Laelia where children, they played the parts of the Army, much like other children play "cops and Robbers" when Nickans last went home and saw that there was still not much progress and the attacks from the Horde we still as big an issue as they were in the second war, he contacted his Sister Laelia and told her of his elaborate plan.
The plan was to create the Vanguard for real, an elite unit of Defenders and Magicians.
The Vanguard currently patrols all areas know to "belong" to the Magocracy Such as Alterac and the Nethergarde Keep in the Blasted Lands.
As well as watching the "home front" the Vanguard also ensures that the Legion is kepts under wraps in Azeroth and Kalimdor and an oath was made to crush the Orcs that have plagued them for so long.
The Scourge is also a target for their war efforts, and while the Scarlet Crusade are not their allies and no war is openly declaired the Magocracy and Vanguard accepts their presence in Lordaeron.
As a rule, Nickans and Laelia refused to be "exclusive" and will allow anyone to join the Vanguard, and welcome High Elves that have not been corrupted as the Blood Elves have been. However, if someone were to join this order they would be submitted to several questions, one of which being "What can you Offer the Magocracy?"