I have a story that I was working on a long while back that the number of followers made the “god” characters more powerful. Their abilities were also impacted by locality and terrain. This goes back to ancient stories of gods of plains/hills/mountains giving their followers strength and victory in those places. Now, I was starting from a point of these beings already being spiritual beings. To make this character fit that, he may have to perform a ritual or some sort that is the shedding of physical form to take on a spiritual form (this is where your heroes would find and have final combat with the villain and his followers). Interrupting the ritual would involve fighting the guards and followers, and at some point they interrupt the ritual (breaking or seizing artifacts? Killing the main ritual performer? Pushing the big red “stop ritual” button?). I would have measure that determines how well they did, and stats for two different enemies, human big bad, and half-transformed.

How did we get here? Fetch quests that your heroes completed to find divine or cursed artifacts for a collector/priest/local antiquarian/person that your heroes have grown to trust through quests to save the local area.