I have a
lot of thoughts about this, so I'm going to break it up into three posts.
First off, I ran a pretty successful BBEG-centered campaign loosely based on Curse of Strahd. I'm pretty terrible at running prepublished adventures or campaigns, so after the Death House I wound up just taking some of the components of Curse of Strahd and making my own campaign. The characters all received visions to come to a secluded valley which was ruled over by a vampire queen and her undead kin. Each character had a reason to wish for the vampire queen's destruction: she cursed their mentor, oppressed their people, had killed their previous adventuring party, or they were a direct witness to her atrocities.
I was inspired by the Tarokka cards to create a system for creating adventures. I made my own cards, in three categories: Settings, Goals, and Complications. In their first adventure (after the Death House, which was a shared dream), the characters rescued Madam Zolenka, a tortle mystic who could read the cards. The cards revealed the path the characters had to take in order to defeat the vampire queen. She could only do three readings per new moon, which allowed me to have three different adventure seeds ready for the players.
Just for fun, I put the cards onto a spreadsheet so I could see what possible adventures awaited the players.
You can check it out here. (Just press delete in order to refresh it.)
Madam Zolenka also told the characters how the people of the valley used to pray to, and received magic from, the stars. But the vampire queen's curse kept the stars obscured by an ever-present miasma of clouds and fog. Whenever the characters completed a task laid out by the Tarokka Cards, they were blessed by the stars with power, and leveled up.
Now you don't have to do a random element like I did (I just enjoyed the challenge of adventure design), but you could definitely plan out your adventures by laying out some locations, goals, and complications. The characters don't have to accomplish all the goals, but each one they do makes the job of facing the BBEG a little easier. You could think of something like...
Location | Goal | Complication |
1. A place connected to a character's background. | 1. Retrieve a powerful weapon. | 1. There's a curse. |
2. A place connected to the BBEG's backstory. | 2. Recruit an important ally. | 2. It's even more dangerous than usual. |
3. A place connected to a character's family. | 3. Eliminate an ally of the BBEG. | 3. The goal has been split into two objectives. |
4. A place where history can be learned. | 4. Gain knowledge about the BBEG's vulnerabilities. | 4. Another powerful organization has taken possession of the goal. |
5. A place that is a safe-harbor for the characters. | 5. Enact a magic ritual to gain more power. | 5. The item retrieved must be repaired; or the person must be healed. |
6. A place of great danger for the characters. | 6. Gain a powerful magic item. | 6. The location of the item or person is unknown. |
Overall this wound up being a really successful campaign that took the characters from 1st to 11th Level. There were some weaknesses to the model, which I can lay out in another post. As a DM, I had a ton of fun designing adventures that were randomly generated.