My own campaign is just about to start "The Hall of Harsh Reflections," having just finished the third of twelve modules. So far they have stayed pretty much on track, but I have had to add several encounters to fill things out and provide context. Diamond Lake has become the town everyone loves to hate, and players are starting to have "favorite" bit part NPCs.
I have an unusually large party (8 players, in fact), which means I must beef up most of the encounters and add additional encounters in order to keep my players "on track" with the assumed advancement of the Adventure Path.
During the course of the Whispering Cairn, you can get a lot of mileage out of the trio of adventurers from Greyhawk whose appearance triggers the entire campaign in the first place. These are natural rivals, and since they are from the Free City you can use them to foreshadow events in future modules that take place there. Khellek is a Seeker, which plays into a very minor subplot in the first adventure. The PCs will get the Seeker ring from Ulavant's corpse and one of them will probably wear it, which makes a nice encounter with Khellek. Auric is there to foreshadow "The Champion's Belt," where he reappears. Tirra is a good "neutral party" and natural interlocutor with the party, particularly with any elves or rougish characters. I worked her into my game by having her play against the characters at a game of "daggers" (darts with thrown knives, essentially) at the Feral Dog. My party has betrayed these guys once, and is afraid of them. That equals fun for everybody, but especially fun for me.
Because my players did a fair amount of Diamond Lake exploration, I was able to work in Balabar Smenk's gang before they appeared as part of the Filge subplot. This lent weight to their later appearance, so I'd strongly recommend putting them in a Feral Dog encounter fairly early in the campaign. My party ended up beheading Kullen right outside the bar, but the other gang members escaped. I made one of them, the bald wizard Merovinn Bask, a real thorn in the party's side. He used a band of hired goblins to invade the PCs' lair in the abandoned mining office, and murdered Ragnolin Dourstone (from "The Three Faces of Evil") right in front of their faces to cover up Smenk's complicity in the cult activity there.
If you can let one of these guys escape the big fight with Smenk's gang, you've got an NPC in your pocket that can spice up the campaign whenever things get slow and boring. A utility player, if you will.
"The Three Faces of Evil" required a great deal of expansion to flesh out the Faceless One/Smenk/Filge connections and to explain Ragnolin Dourstone's backstory and purpose. He is one of the few major campaign NPCs that wasn't detailed in the outline, and as a result I had to do a little more work to incorporate him into the story.
The main part of "Encounter at Blackwall Keep" is playable in two or three sessions, which is way faster than the first two (at least in my campaign). In order to maintain the pace and to make sure that my players absolutely _hated_ the Mistmarsh and considered it a sweltering deathtrap, I really played up the multi-day journey from Blackwall Keep to the Twisted Branch lair. I made extensive use of random encounters (really planned encounters based on the random encounter chart), relying heavily on giant crocodiles and a covey of green hags. I also threw in a semi-humorous encounter with a wandering bullywug named Groak and his giant toad Chlub-Chlub.
The PCs' fight against the lizardfolk outside Diamond Lake went absurdly well for the PCs. Disappointingly so, from my perspective, but I think the players enjoyed the opportunity to cut loose a little. Using some incredibly sweet terrain we have in the office, I designed a new encounter with lizardfolk in a ruined, half-submerged temple on the way to the Twisted Branch lair. I populated it with a druid (using Hishka's stats but with a different name and personality) and lots of warriors, plus two giant snakes and several poison dusk lizardfolk archers. The fight killed two PCs, but it's one everyone will remember for a long time.
After the PCs defeated the Twisted Branch lair (a cakewalk), the PCs learned that their two new companions, who they met lost in the swamp, had been with an ill-fated adventuring group that was raiding for treasure in a bullywug lair deeper in the swamp. The leader of the enclave? Prince Groak, of course.
The Twisted Branch behind them, the party continued north in hopes of finding warm beds in Blackwall Keep. Taking a cue from a great idea posted on the Paizo boards, I told the players to put away their characters and had them build first-level human warriors using the standard array. I gave each character a longsword, a torch, a crossbow, and some chainmail armor. I had them roll between one and three times on the random NPC personality trait table in the DMG, and made them guards in Blackwall Keep, a dead-end assignment for n'aer-do-wells and losers.
Then I had them investigate the spawn of Kyuss in the basement. These guys can't even take a single hit from a spawn of Kyuss and live (so I weakened the spawns' Strength bonus, just for the sake of a better game), so having the spawn mow through the "normal" characters allowed me to foreshadow the gross worm effects of the spawn of Kyuss in a truly horrifying way. It was a grotesque horror movie, and it was a nice departure from weeks of slogging through the Mistmarsh.
And that brings us to the session that ended a couple of hours ago. By fleshing out the minor characters and using Diamond Lake as an integral "character" in the campaign storyline, I've been able to work in lots of extra fights organically, rather than grafting another pre-packaged adventure onto the beast.
It's certainly more work, but work is half the fun of being the DM.
--Erik
