Cool; I have questions.
What points were the characters, how many?
Four 300-point PCs (knight, swashbuckler, scout, and wizard). Obviously not the equivalent of 1st level AD&D characters! I had limited time for prep, so I just decided that any members of the cult would have access to "reptile spirit" power-ups. Probably different for each individual to make it more interesting (and spooky). So maybe one can invoke "reptile skin" and gain a boost to damage resistance. Another has a poisonous touch (or bite). Another's arms can turn into snakes (or maybe multi-headed snakes), providing multiple attacks and/or constriction. Maybe some snake eye mesmerism. That sort of thing. I figured that I would just adjust the seasoning on the fly until things felt balanced.
As it played out, we didn't have any combat during the first session. It was all role-playing and exploration. We ended on a cliffhanger that will lead to a fight next time. I have some time to make more specific decisions.
What did you use for the final boss?
I haven't thought that far ahead—I knew there was no way they would get that far—but my vague plan aligns with your thinking. I'm going to read over the existing Naga and dig through
Serpents of Legend for inspiration.
Any hiccups to warn me about?
Nothing yet. We had a lot of fun. The players enjoyed exploring the town, interacting with locals, deciding which inn to trust, and finding out where to get the best beverages. They ultimately rented rooms at both inns to see if they could provoke something. One character had the Poisons skill and discerned the sleeping poison in the "on the house" wine that was left in their room at the cultist inn. So they pretended to drink it and fell asleep, but they're fully armed and ready. We ended just as the cultists came in through the secret door. With only two PCs in the room (the other two are at the other inn), it is likely to be a challenging fight. Though the cultists aren't expecting the PCs to be ready for them.
Have you run it yet?
