Lesser Order of Oberon

You may be looking for the Grand Order of Oberon.

The Lesser Order of Oberon was an order of assassins. One guild bought Brian the Ood and performed the operation to remove his hindbrain themselves in a dark basement, which he claimed was rough and very painful. They brutally trained him, with only one of Brian's trainers giving him any positive feedback. As a result, Brian killed that trainer first, giving him a quick end, before going on to kill the entire guild. (AUDIO: The Minds of Magnox)