Society of Bone
"Ah, my friend, I sometimes forget how new you are to our fair city. No money needs to change hands for me to answer this question for you. I deal in secrets, and what I'm going to tell you is something that most Khezvarans have known for centuries. If the grim work you're considering needs to be done, you'll want the Society of Bone. Their methods are a tinge peculiar, but their results are are without question. When it's time to bring your proposal to them, you'll need to write your problem's name, occupation, and location on a piece of parchment. Include any other identifying information you can: identifying scars or tattoos, known associates, anything you have. If they can't be positive of the target, the Bonesmen won't take the contract. When you've prepared your note, roll it up and place it in an empty poison bottle and seal the stopper with melted wax. When the moon is up, take the bottle to the Remembrance Gate of The Necropolis and leave it among the roots of the yew tree just outside the gate. Then light a black candle and stand at the gate facing Griffon Hill until it burns all the way down. Don't worry about being seen. The life expectancy of anyone who interferes with Society business is measured in meals. After a few guards turned up dead, even the thick-skulled imperials who patrol Arena Ward learned to report nothing out of the ordinary at the bridge without getting within arrow's range of the river. No, in the unlikely event that you run into anyone at Mourner's Point, it means they're up to the same sort of business you are, which should be plenty of incentive to pretend you never saw one another. Assuming they can confirm the target and think you can pay, they'll come to you--usually in a way that makes it clear that the only thing preventing you from being their next victim is a lack of someone willing to pay their fee. After going over the particulars, the Skullhead will name the price, which is not subject to negotiation. They'll want half of it before they do the deed, and once it's paid your problem will be gone before the next new moon. "
References to the Society of Bones can be found in documents from as far back as the time of the Dragon Pacts, but the date of the cult's founding and the degree of continuity between the group referenced there and the modern organization are unknown. The Society has been outlawed practically since its inception, but this is a matter of law, not fact. Neither the Ispans of old nor the more recent imperial authorities have ever seriously sought to enforce the ban. Whether this reluctance to go after the Bonesmen owes more the useful service the Skullheads provide or the authorities' desire to avoid being assassinated is debatable.
Tenets of Faith
The Society of Bone's purpose is to provide a steady stream of corpses for The Lord of Bones to carry away to his realm. They believe that by currying favor with Old Rot, they'll be able to avoid the judgement of Argalak the Weigher when they die and instead receive a fiefdom to rule in the Carrion Moors. Beyond that, the particulars of the Bonesmen's beliefs and religious observances are known only to themselves.
In their work as hired assassins, the Bonesmen have a reputation for discretion and efficiency. The only real complaint about their work is that they charge considerably more to conceal that the target has been assassinated. They'd much prefer to advertise their kills by painting their victim in a skull mask--reputedly part of a ritual to make the corpse easier for the Lord of Bones to capture--and leaving the body on display in some prominent public space.
Political Influence & Intrigue
While they can play an important role in the political intrigues of the city, the Bonesmen do not engage in politics themselves. They will take a contract from anyone who can pay their price, regardless of ideology or faction.
The Sisters of Misery were a group that splintered off from the Society of Bone during the early days of imperial occupation. They are widely believed to have been responsible for the Fifty Day Fire.