I'm rewriting the second adventure of RotR.
For the first half of the adventure: I replace the Aldern's ghast template with fleshbound vampire (CR +1) and envious creature (CR +2). So, I now have a tragic CR 9 villain, and instead of a horde of ghouls Sandpoint could find themselves threatened by a group of (weakened) vampires. For the fun of the players, off course :D
Now, for when the players arrive in Magnimar. Although Karzoug is the BBEG, in this AP i see several references on Lamashtu. I saw the Module "Broken Chains", and I got an idea.
Nualia and Ironbriar have no connection. Instead, when the aasimar fled to Magnimar, he met a priest of the Mother of Monsters. He taught her the mysteries of Lamashtu, and later he gave Nualia the Sihedron medallion.
Five years later, and the AP begins. Nualia, back on to the Lost Coast, gathers herself a group of mercenaries and convinces the warchief goblin to join forces to free Malf and destroy Sandpoint. Meanwhile, the priest of Lamashtu has a group of followers composed of addicts and scum of the worst kind. They are hiding in the Underbridge, in the basement of an abandoned shrine of Sarenrae, and kidnap women for their horrible rites.
Since Underbridge is the poorest and infamous Magnimar's district, the law enforcement have ignored the complaints of disappearance in that area. But when the Skinsaw Cult started to killing, the citiziens accuse the mayor of non-fulfillment. So, the Justice Ironbriar is in charge of investigating the case, and his men carry out investigations and interrogations.
Or at least that's what you believe. Indeed, Ironbriar is the leader of the Skinsaw Cult; it is aware of the existence Lamashtu's followers in Magnimar since one of the Skinsaw's cultist tried to kill the Lamashtu's priest (and the cultist was later captured and tortured to death by the priest). So, there are two evil cults that are a secret war in Magnimar, between the followers of Norgorber and those of Lamashtu. When the Skinsaw Cultist began to mark and kill the locals, Ironbriar has already identified the perfect scapegoat to deflect investigations on those truly killers, and he knows the location of their hideout.
However, instead of sending his assassins to fight the demonic cultists, it intends to use the PCs! When they arrive in Magnimar and begin to investigate, they might come to know there is a judge who is handling the case (ie Ironbriar) and would then talk to him. Ironbriar (in my campaign is an inquisitor rather a cleric) appear stern but fair, and it does not hide the party who has his suspicions.
Then he pulls out a Lamashtu's unholy symbol, declaring that it was found on the site of the last murder (partially true: it was actually placed by one of the Skinsaw cultists when he finished work, then being found by the city guard. Having faced Nualia, the PCs will think that behind the murders of Sandpoint can hide some revenge of the Lamashtu's church (especially if Nualia were to escape from the coming battle against them). Ironbriar then suggest the PCs to go to investigate in Underbridge 'cause the last murder took place there.
Ironbriar knows that the PCs are the Heroes of Sandpoint, and intends to reach out to them a trap. It will make them come to terms with the Lamashtu's followers hoping to kill them, but if they were to survivethen will send his men to finish them.
So, i use the two Module with the following changes:
* The Lamashtu's followers found in the sewers of the city. One of the quickest ways to reach them is through the basement of the abandoned shrine, since they are linked
* The shrine in question is avoided by the inhabitants of Underbridge, since they consider accursed (the priest of Sarenrae was killed shortly after he built the structure). It is still occupied by addicts; these are enslaved by the Lamashtu's priest using a drug, and act as eyes and ears for the CE worship
* The last woman kidnapped is a Pathfinder, belonging to the Magnimar's lodge. Venture-Captain Sheila Heidmarch is very angry with the mayor's lazy, and it decided to offer a reward to anyone with news of the Pathfinder (a way as any to make known to the players this faction)
* I remove all gnolls, the yaenit and the Midwife by Broken Chains. From Dawn of the Scarlet Sun i remove Zadendi and Avalexi while the Scarlet Son become a normal gargoyle
* From Broken Chains I keep the slaver thugs, Tinderwick, Fayaz, the lamasthan cultist and Black Milk Mother
* I will use the stats of "Wrath Priest" (NPC Codex) as the leader of lamasthan, It may be okay? Moreover, if in the first adventure Nualia should survive, could find refuge here (and then the meeting could rise GS), what could happen? Finally, I have already prepared a CR 6 battle (four Skinsaw Cultist): these cultists follow the PCs at a distance, even in the sewers, and attack when they believe they have the perfect opportunity (for example, wait for the PCs are exhausted after a battle against a otyugh)