COSM - The Circle of Sequestered Magicks
Presented here are 3 Tiers of information, going from the most common that most people even at light education or historical knowledge will know, then work up into what most scribes would be able to tell you, and finally what only sages or specialized classes would know.
Tier 1:
The Circle was founded by many of the fathers of various magic academies and even entire schools of thought. It was rumored that even figures such as Mishra, Mordekainen, and Elminster were at one point patrons if not full members of the COSM. The Circle's principle purpose was to regulate the magicks used by the orders of all races and do whatever was neccesary to prevent magicka of incredible power from falling into the wrong hands. Recognizing the immense duty this entailed, the COSM was expanded and broken into cells scattered across the planet and some rumored that they even trascended the Planar dimensions in order to prevent the induction of powerful forces not born of the Material Plane. The COSM has made a personal mission out of sealing away and destroying the darker magics such as Necromancery.
Tier 2:
The Circle's founding member and rumored still living father, Urza had created a set of items that were to be used in defense of the Material Plane and Order in general. The main branch of the COSM as well as each cell still seeks out particularly capable men and women, however it is also rumored that these searches are not exclusive to magic-weavers. While COSM's existence has been acknolwedged by a few nations they still operate largely underground.
Tier 3:
Recently, COSM has suffered a schism from some of the older members, and they have gone missing. The story is that the exile happened as result of them preaching dark magics and other related activities. For now, those exiles have gone off the map concealing themselves from even the COSM raising concern amongst the community that they are up to something.