A cult worshipping the demigod Night Wyrm, accessible to anyone marked by a divine suffering artifact.
Carl's new elbow tattoo, the The Night Wyrm's Nasty Little Web of Suffering, grants him access to the Guild of Suffering. He has never read anything about it, so Mordecai explains: it is a cult, neither a real guild nor a real church, similar to the city elves of the third floor. They maintain outreach centers, though Mordecai has never been inside one.
They worship the Night Wyrm, a demigod who is not a regular member of the pantheon — similar to Samantha, and a long story. The cult possesses something called a Memorial Crystal, akin to a soul crystal, though what it actually does has never been established. It is all tied to Carl's Ring of Divine Suffering; a few seasons back, the entire seventh floor was centered on the cult raising their god. Everybody who uses a divine suffering artifact gets marked as Carl now is — Princess Donut notes she never noticed the mark on Frank or Maggie.
The shadowy cult behind the ring of Divine Suffering, now formally open to Carl.