The Obsidian Legion were a post-Dominion War Cardassian faction that vied for control of the Cardassian Union in the aftermath of that conflict. One of the smallest factions it was made up of both former and active members of the Obsidian Order. They sought to return the Union to a pre-war state but with the Order in control of the Union. They did not participate in the political process in any legitimate way preferring to use assassination, blackmail and theft to increase their power. (The Dominion War Sourcebook: The Fires of Armageddon)