I knew that one of the PCs would have to sacrifice themselves to save Arcanis, so I had a contingency plan all along to rescue whoever that was. Since that was Sebastian, arguably the most destructive character in the group, it meant that any adventure involving undead was going to be that much harder.
However, the last time our heroes faced off against ghosts, way back in Madness in Freeport, they were unprepared. Since then, both Kham and Vlad acquired ghost touch weapons. And both of them have bane weapons against Carcosan beings, which is precisely what they were up against. I changed many of the infernal references to Carcosan references instead, and gave just about everything that wasn’t undead has the Farspawn template.
That said, one big difference in how the heroes approached this adventure is that they had a mission. In the original version of this adventure, the goal is to find the children lost in the house, which means tearing the place apart. Instead, I changed the party’s goal: find the portal to Carcosa. They know it’s in the basement. And if you think about it, aren’t all portals to horrible places in the basement?
This means the adventure goes very quickly. Our heroes are in no mood to explore; they want to find the portal and get the hell out of there. So they skipped a whole section of the module with almost no prodding from me. Indeed, they made a beeline straight for the portal without knowing where it was!
What was supposed to be a creepy haunted house ended up being more like a raid on a drug den. But the adventure bridged the gap to Carcosa, and in that regard it was definitely a success.