Assassin's Guild

So, the Order of the Green Hand needs an assassin's guild to go with it, no? Taking a cue from Zak, I'm presenting this guild as all rules, with any "fluff" I think has to be included in brackets. This assassin's guild doesn't have any official name, but goes by a few unofficial names, including "the Group," "the Gang," "the Workmen," and, most commonly, "the Monopoly."

Guild Law:

• Guilded assassins may not kill other guilded assassins, on pain of death.
• Guilded assassins may take apprentices, who are not considered guilded, but who may kill under their master's supervision. [Apprentices are the way enemy Guild members get rid of each other.]
• Apprentice assassins may only gain guild membership by replacing a retiring guilded assassin, killing a guilded assassin and taking his place or by co-founding a Guild franchise in a new location.
• So long as it is expedient to do so, guilded assassins have the responsibility to kill any non-guild murderer they become aware of in an area claimed by the Guild. The cornerstone of the Guild is its violent insistence that it have a monopoly on killing. [This leads to clashes with the Thieves Guild, who like to keep everything, including hits, in-house instead of sub-contracting with a specialist guild.]
• Guild assassins may take any job they choose, but must complete any job they accept. If they fail, they must try again until they succeed.

Characters from any class may become an assassin's apprentice, but they also keep all of their class restrictions. Assassin is a Glantri-style prestige class that I'm working on, but Dyson also has a Glantri-style Dark Assassin you could use.