So I want to change the whole Lucky Bones scenario up a bit, since I don't really like how it plays out in the book and the map of the dungeon is pretty bad as well. I want a bit more of a investigation and social RP going on before the players go in and murder hobo their way through the mini dungeon.
I am going to upscale the whole operation. The cult of Mahathallah is using the (still intact) gambling house as a public front to hide their secret agenda. The cult is lead by a (storm?) hag and the changeling cultists are her daughters who were drawn to her by the calling, which hopefully should make Luculla a more interesting NPC (can the PCs pull her away from her mother or will she stay loyal?).
I really want to use a Gambling Devil, so one of them will operate the public gambling side of things. A underground VIP area will lead into the illegal parts of the cult, with a high roller table operated by a ghost (but of course ;D) and personal booths for recreational opium enjoyment. The changelings will be the hosts in this area of the Lucky Bones.
So behind all the gambling is a whole drug and human trafficking operation going on. Drugs and sacrifices are both integral parts of worshiping Mahathallah, so I think this should fit nicely.
This should also make the sudden Skum/Aboleth plot and the excursion in book 3 a bit more organic. The cult abducts people for the Skum to deliver to Menotheguro and in exchange they will gain knowledge from the Aboleth.
My players have earlier "allied" themselves with the Red Jills (under new leadership), which could give them another way to get into the whole illegal operation that the cult has going on.
In the grand scale of the campaign, my idea is that Barzillai used the services of the cult to abduct Jilia Bainilus. I think the knowledge that he used the cult to further his own plans while f*##ing them over with the corruption of the soul anchor fits his personality.
And uncovering that connection is what sealed the fate of Octavio and the whole Order of the Torrent. It will also be the reason why he points the PC in the direction of the cult. This way they have more of a reason to investigate the Lucky Bones, besides just wanting a bigger hideout.