There are some missions that are too gruesome, too costing to a man’s soul for even members of the Inquisition. For these missions, there is a specialized chapter of assassins ,trackers, and special forces called the Witch Hunters. These men and women work in small teams of 2-7, searching for and eliminating Mages and magical creatures where they are found. They are excellent combatants against those who practice magic, having trained for many years against demons on Guerre and other planets and been hand picked for the jobs at hand. These men and women do not fight on the front lines save for rare occasions, and often work separated from the chain of command for weeks, or even months at a time on missions that take them out of the Reich's territory or influence. These Witch Hunters are the most feared people in the Inquisition by mages, and to earn a team hunting you down, you must go above simply practicing magic, to the point of being a risk to the galaxy and her people. No task is too evil or too gruesome for these people.
These men and women have earned the very best. Whenever the Reich makes new technology, they test it and acquire access to it before anyone else. Whenever there's a mission that needs to be done quietly, it's the Witch Hunters. If there's something to be done under cover, the Witch Hunters are called. The Witch Hunters are the Reich's most fearsome, and most loyal subjects, never deviating from their paths.